For my dermatology practical exam please give me a proper case description of “nevus of ota” and also prepare me extensively for the questions that examiner can ask from medium to hard to very hard

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Nevus of Ota is a broad practical-exam topic. We can prepare it in an examiner-oriented sequence:

Standard long-case description: history, morphology, distribution, examination, diagnosis, and differential diagnosis.
Core viva: definition, nomenclature, epidemiology, etiopathogenesis, and classification.
Medium-level questions: differentials, Wood lamp findings, ocular involvement, histopathology, and associations.
Hard questions: dermal melanocytosis biology, segmental distribution, complications, and investigations.
Very hard questions: melanoma risk, surveillance, treatment physics and laser selection, counselling, and unusual variants.
Rapid-fire mock viva: examiner questions with model answers and common traps.

At a high level, nevus of Ota, also termed oculodermal melanocytosis, is a congenital or early-onset form of dermal melanocytosis. It presents as unilateral, slate-grey to blue-brown macular pigmentation in the ophthalmic and maxillary divisions of the trigeminal nerve, often with pigmentation of the sclera, conjunctiva, or other ocular structures. The key practical priorities are to recognize its characteristic distribution, carefully look for ocular involvement, distinguish it from other pigmentary disorders, and explain the small but meaningful melanoma and glaucoma-related surveillance considerations.

Which preparation format do you want?

Full practical case + viva
Only examiner questions and answers
Mock viva, medium to very hard
One-page last-minute revision sheet

Case description and viva answers

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oculodermal melanocytosis

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Nevus of Ota oculodermal melanocytosis glaucoma melanoma surveillance ophthalmology review

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https://www.ncbi.nlm.nih.gov/books/NBK560574

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Nevus of Ota oculodermal melanocytosis unilateral blue gray facial patch scleral pigmentation clinical photograph

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Nevus of Ota: Practical Case Description

How to present the case

This is a case of nevus of Ota, also called oculodermal melanocytosis or nevus fuscoceruleus ophthalmomaxillaris.

A young female patient presents with an asymptomatic, non-scaly, bluish-grey to slate-brown patch over the left side of the face, present since birth or early childhood and gradually becoming darker and more extensive around puberty. There is no history of itching, pain, bleeding, ulceration, preceding inflammation, trauma, or application of topical medications. There may be cosmetic concern.

On cutaneous examination, there are multiple, coalescent, ill-defined, mottled blue-grey to brown macules forming a patch over the periorbital area, forehead, temple, malar region, and side of the nose, predominantly in the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve. The lesion is usually unilateral. There is no surface change, scaling, induration, atrophy, or altered sensation.

On mucosal and ocular examination, ipsilateral slate-grey pigmentation may be present over the sclera or episclera, conjunctiva, iris, and occasionally palate, nasal mucosa, or tympanic membrane. The pigmentation is non-blanchable. Hair and nails are normal. There is no regional lymphadenopathy.

A complete ophthalmological examination is required, including visual acuity, slit-lamp examination, intraocular pressure measurement, gonioscopy, and dilated fundus examination to look for ocular melanocytosis, glaucoma, and uveal melanoma.

Provisional diagnosis: Left-sided nevus of Ota with ocular involvement, if scleral or episcleral pigmentation is present.

Differential diagnoses: Mongolian spot or congenital dermal melanocytosis, blue nevus, nevus of Ito, acquired bilateral nevus of Ota-like macules or Hori nevus, post-inflammatory hyperpigmentation, melasma, lichen planus pigmentosus, drug-induced pigmentation, and, where relevant, melanoma.

One-Minute Case Summary

“This patient has an asymptomatic, unilateral, ill-defined, mottled slate-grey to blue-brown macular pigmentation over the left periorbital and malar region in the territory of V1 and V2 of the trigeminal nerve, with ipsilateral scleral pigmentation. The lesion began in early life and has slowly increased in pigmentation. There are no inflammatory or malignant features. These findings are consistent with nevus of Ota or oculodermal melanocytosis. I would refer for detailed ophthalmological evaluation because of the risks of ipsilateral glaucoma and uveal melanoma.”

Viva Questions With Model Answers

A. Basic and Medium-Level Questions

1. What is nevus of Ota?

Nevus of Ota is a benign form of dermal melanocytosis characterized by unilateral blue-grey, slate-brown, or blue-black facial pigmentation in the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve, often associated with ocular pigmentation.

2. What are its synonyms?

Oculodermal melanocytosis
Nevus fuscoceruleus ophthalmomaxillaris
Congenital melanosis bulbi
Oculomucodermal melanocytosis

Dermatology, 2-Volume Set, 5e, p. 2362.

3. Why is it called oculodermal melanocytosis?

Because it involves both:

Dermis, especially facial skin
Ocular structures, such as episclera, sclera, uvea, iris, and sometimes conjunctiva

4. What is the typical colour?

Blue-grey, slate-grey, blue-brown, brown, blue-black, or rarely purple.

5. Why does it appear blue?

The blue colour is due to the Tyndall effect. Melanin deposited in deep dermal melanocytes scatters shorter wavelengths of light back to the observer, producing a blue or grey appearance.

6. What is the usual distribution?

Usually unilateral, in areas supplied mainly by:

Ophthalmic division of trigeminal nerve, V1
Maxillary division of trigeminal nerve, V2

Typical sites include forehead, temple, eyelids, periorbital area, malar region, nose, earlobe, and preauricular or retroauricular areas.

7. Which trigeminal divisions are affected?

Classically V1 and V2. V3 involvement is less common.

8. Is it always unilateral?

No. It is predominantly unilateral, but bilateral involvement can occur in approximately 5% to 15% of cases. Dermatology, 2-Volume Set, 5e, p. 2362.

9. At what age does it present?

There are two peaks:

At birth or in infancy
Around puberty

Some lesions become more conspicuous at puberty. Dermatology, 2-Volume Set, 5e, p. 2362.

10. Does it resolve spontaneously?

No. Unlike a typical Mongolian spot, nevus of Ota generally persists lifelong and may become darker or extend gradually over time.

11. In whom is it more common?

It is more common in individuals of Asian ancestry and in people with darker phototypes. There is female predominance.

12. What is the female-to-male ratio?

It is reported much more commonly in females. About 80% of reported cases occur in females, although cosmetic consultation bias may contribute. Dermatology, 2-Volume Set, 5e, p. 2362.

13. Is it hereditary?

Usually no. It is generally sporadic, although rare familial cases have been described.

14. Is it a hamartoma?

It is regarded as a hamartomatous proliferation or persistence of dermal melanocytes. The relatively greater density of dermal melanocytes compared with simple dermal melanocytosis supports this concept.

B. Pathogenesis and Histopathology

15. Explain the embryological basis.

Melanocytes are neural crest-derived cells. During embryogenesis, melanocyte precursors normally migrate to the epidermis. In nevus of Ota, some melanocytes remain or become trapped in the dermis, where they produce melanin.

16. What is seen histologically?

Histology shows:

Elongated, spindle-shaped or dendritic melanocytes
Melanin pigment within these melanocytes
Cells scattered between collagen bundles in the dermis
Often located in the upper reticular dermis
Sometimes present around blood vessels, sweat glands, and sebaceous glands
Epidermis is usually normal, although basal hyperpigmentation may occur

Dermatology, 2-Volume Set, 5e, p. 2362.

17. Which stains are useful?

Fontana-Masson stain: Demonstrates melanin.
Melan-A/MART-1, HMB-45, S-100, SOX10: Highlight melanocytic cells.
Bleaching of melanin can assist histological assessment where pigment obscures cellular details.

18. What molecular mutations are associated with nevus of Ota?

Somatic activating mutations in GNAQ and GNA11 have been reported. These genes encode G-protein alpha subunits and are also relevant in blue nevi and uveal melanoma.

19. Why is the GNAQ mutation important?

GNAQ activation promotes melanocytic proliferation and survival through downstream signalling pathways. It provides a molecular link between dermal melanocytoses, blue nevi, and uveal melanoma, though nevus of Ota itself is usually benign.

20. What additional mutation may be found in lesions progressing to melanoma?

BAP1 alterations have been reported in cases showing progression to melanoma. This is not a routine diagnostic test for every patient but is relevant to malignant transformation. Dermatology, 2-Volume Set, 5e, p. 2362.

C. Ocular Involvement and Complications

21. What ocular structures can be involved?

Episclera and sclera
Conjunctiva
Iris
Choroid and fundus
Ciliary body
Retina
Optic nerve
Extraocular muscles
Retrobulbar fat

22. Which ocular finding is most common?

Ipsilateral scleral or episcleral pigmentation is common. In approximately two-thirds of patients, the ipsilateral sclera is involved. Dermatology, 2-Volume Set, 5e, p. 2362.

23. How do you distinguish episcleral melanocytosis from conjunctival pigmentation clinically?

In episcleral pigmentation, the pigment is deep and the conjunctiva can be moved over it with a cotton-tipped applicator after topical anesthesia. True conjunctival pigmentation moves with the conjunctiva. The Wills Eye Manual, p. 368.

24. What are iris mammillations?

They are multiple small, evenly distributed, nipple-like elevations over the iris surface. They may be associated with ocular or oculodermal melanocytosis and can be a clue to increased melanoma risk.

25. What is the important glaucoma association?

Glaucoma may occur, usually ipsilateral to the pigmentation. Mechanisms include pigment accumulation in the trabecular meshwork and developmental abnormalities of the iridocorneal angle, impairing aqueous outflow.

26. What type of glaucoma occurs?

Most commonly secondary open-angle glaucoma, though angle abnormalities may also be present.

27. What is the approximate risk of glaucoma?

About 10% of patients may develop glaucoma. Dermatology, 2-Volume Set, 5e, p. 2362.

28. What malignancy must be excluded?

Uveal melanoma, especially choroidal melanoma.

29. What is the estimated risk of uveal melanoma?

A commonly quoted estimate is approximately 1 in 400 affected White patients. The risk is lower in Asian populations but still warrants surveillance. The Wills Eye Manual, p. 368.

30. Which other melanoma sites can occur?

Rarely:

Cutaneous melanoma within the lesion
Orbital melanoma
Meningeal or leptomeningeal melanoma
Melanoma involving the chiasm or central nervous system

31. Which patient should raise your suspicion for malignant transformation?

A patient with:

New papule, nodule, or plaque within the patch
Rapid enlargement
New asymmetry or irregularity
Change in colour, especially variegated colour
Ulceration or bleeding
New ocular symptoms, visual loss, field defect, photopsia, or pain

A suspicious skin lesion should be biopsied, and suspected ocular disease needs urgent ophthalmology or ocular oncology assessment.

32. Does nevus of Ota usually impair vision?

No. Vision is generally preserved, but complications such as glaucoma or uveal melanoma can threaten vision.

D. Examination and Investigations

33. Is biopsy necessary in every case?

No. Diagnosis is usually clinical. Biopsy is indicated if:

The diagnosis is uncertain
A lesion becomes raised, nodular, rapidly changing, ulcerated, or otherwise suspicious
Malignancy needs exclusion

34. What investigations will you do?

Detailed dermatological examination and clinical photographs
Slit-lamp examination
Intraocular pressure measurement
Gonioscopy
Dilated fundus examination
Ophthalmic imaging if indicated, such as ocular ultrasonography, OCT, fundus photography, autofluorescence, or ultrasonographic biomicroscopy
Skin biopsy only for suspicious change

35. What is the role of dermoscopy?

Dermoscopy can assist in documenting pigment distribution and detecting atypical features. It does not replace clinical and ophthalmological assessment when ocular melanocytosis is present.

36. What will you advise regarding follow-up?

Baseline ophthalmological assessment and at least annual follow-up, including intraocular pressure and dilated fundus examination. Dermatological review is also appropriate, particularly if a lesion changes.

This approach is supported by ophthalmology reviews and clinical references because glaucoma and melanoma are uncommon but important complications. The ophthalmology review of oculodermal melanocytosis explains the mechanisms and follow-up importance.

E. Differential Diagnosis

37. Differentiate nevus of Ota from Mongolian spot.

Feature	Nevus of Ota	Mongolian spot
Site	Face, especially V1 and V2	Lumbosacral region, buttocks
Ocular involvement	Common	Absent
Course	Persists lifelong	Usually fades in childhood
Colour	Blue-grey, slate-brown	Blue-grey
Laterality	Usually unilateral	Often symmetrical or midline
Complications	Glaucoma and uveal melanoma risk	No usual ocular or melanoma association

38. Differentiate nevus of Ota from nevus of Ito.

Feature	Nevus of Ota	Nevus of Ito
Main site	Face and periocular region	Shoulder, supraclavicular, scapular, and deltoid region
Nerve distribution	V1 and V2 trigeminal territory	Posterior supraclavicular and lateral cutaneous brachial nerve territories
Ocular involvement	May occur	Usually absent

Nevus of Ito is also called nevus fuscoceruleus acromiodeltoideus.

39. What is Hori nevus?

Hori nevus is acquired bilateral nevus of Ota-like macules, also called acquired dermal melanocytosis. It generally occurs in adult women as bilateral blue-brown macules over the malar areas and lacks ocular involvement.

40. Differentiate from melasma.

Melasma is usually:

Bilateral and symmetrical
Brown rather than slate-blue
Predominantly epidermal or mixed pigmentation
Occurs on centrofacial, malar, or mandibular areas
Has no scleral pigmentation or glaucoma/melanoma association

41. Differentiate from lichen planus pigmentosus.

Lichen planus pigmentosus commonly shows diffuse or reticulate grey-brown pigmentation on photoexposed sites, often with a history of inflammatory lesions or associated lichen planus. It is not limited to trigeminal distribution and does not involve the sclera.

42. Differentiate from blue nevus.

Blue nevus is usually a localized, well-circumscribed blue-black papule or nodule, not a broad facial patch with ocular involvement.

43. Differentiate from post-inflammatory hyperpigmentation.

Post-inflammatory hyperpigmentation follows an inflammatory process such as acne, dermatitis, injury, or a drug eruption. It is generally brown to grey-brown and lacks the congenital pattern, trigeminal distribution, and scleral involvement of nevus of Ota.

F. Treatment Questions

44. Is treatment necessary?

No, because it is benign. Treatment is mainly for cosmetic distress. However, ophthalmological surveillance is medically necessary when ocular involvement is present.

45. What is the treatment of choice for cosmetic improvement?

Q-switched pigment lasers or picosecond lasers.

Common options include:

Q-switched Nd:YAG laser, particularly 1064 nm
Q-switched alexandrite laser, 755 nm
Q-switched ruby laser, 694 nm
Picosecond lasers

Andrews' Diseases of the Skin, p. 731.

46. Why are Q-switched lasers used?

They produce very short, high-energy pulses that selectively target melanin. This causes photoacoustic fragmentation of dermal melanosomes while limiting damage to surrounding tissue. The fragmented pigment is cleared gradually by macrophages.

47. Why is 1064 nm Q-switched Nd:YAG especially useful in darker skin?

The longer wavelength penetrates more deeply into the dermis and has relatively lower epidermal melanin absorption than shorter wavelengths. This makes it suitable for a broad range of skin phototypes, though post-inflammatory pigment alteration remains possible.

48. What are laser adverse effects?

Transient erythema and edema
Crusting or blistering
Post-inflammatory hyperpigmentation
Hypopigmentation
Textural change or scarring, uncommon with proper technique
Incomplete response and recurrence or re-darkening
Ocular injury if appropriate eye protection is not used

49. Are topical depigmenting agents alone effective?

They have limited benefit because the pigment-producing melanocytes lie in the dermis. They may sometimes be used to reduce superficial epidermal melanin before laser treatment, but they do not remove the underlying dermal melanocytosis.

50. What counselling will you provide before laser treatment?

Explain that:

Multiple sessions are often needed.
Response is gradual and may take months.
Darker skin has greater risk of post-inflammatory hyperpigmentation.
Strict photoprotection is advisable.
Treatment is cosmetic and does not remove the need for eye surveillance.
Any ocular treatment must be undertaken with specialist protection and coordination.

Hard and Very Hard Viva

51. Why can a benign dermal melanocytosis be associated with melanoma?

Both nevus of Ota and uveal melanoma involve melanocytic populations and may share activating mutations in G-protein signalling genes such as GNAQ/GNA11. Additional genetic events, such as BAP1 loss, may contribute to malignant transformation in a minority of lesions.

52. Does laser treatment reduce the risk of uveal melanoma?

No. Laser treatment improves visible cutaneous pigmentation but does not eliminate melanocytes in ocular structures or negate the need for ophthalmologic surveillance.

53. Why is melanoma surveillance particularly important in White patients?

Uveal melanoma arising in association with ocular or oculodermal melanocytosis is reported relatively more often in White populations, although surveillance is appropriate regardless of ethnicity.

54. What is the mechanism of glaucoma in this condition?

Pigment deposition and melanocytic infiltration can affect the trabecular meshwork and Schlemm canal, leading to reduced aqueous outflow. Developmental angle anomalies can also contribute.

55. What is the significance of a darker ipsilateral iris?

It indicates ocular melanocytosis involving the uveal tract. It should prompt a detailed ocular examination for associated angle pigmentation, glaucoma, and choroidal melanocytosis.

56. What does the term “melanosis bulbi” mean?

It refers to pigmentation involving ocular structures, especially sclera or episclera, in association with ocular melanocytosis.

57. Is the lesion truly distributed along peripheral nerves?

The clinical pattern resembles trigeminal distribution, but the exact pathogenesis is not a peripheral nerve lesion. It reflects the distribution of persistent dermal melanocytes in characteristic facial territories.

58. Can nevus of Ota involve mucosa?

Yes. It may involve conjunctiva, palate, buccal mucosa, nasal mucosa, pharynx, tympanic membrane, and external auditory canal.

59. What is phakomatosis pigmentovascularis, and what is its relevance?

It is a group of syndromes involving coexisting pigmentary nevi, often dermal melanocytosis, and vascular malformations such as nevus flammeus. Nevus of Ota may occur as part of this spectrum. Such patients need assessment for extracutaneous and ocular involvement.

60. What neurological syndrome may be associated with extensive pigmentary involvement?

Rarely, extensive oculodermal melanocytosis may be associated with melanocytic proliferation in the meninges, including meningeal melanocytoma or leptomeningeal melanocytosis. Neurological symptoms warrant neurological assessment and imaging.

61. What are red flags in an established nevus of Ota?

New raised or firm nodule
Sudden rapid change in colour or size
Ulceration, bleeding, or persistent pain
New visual symptoms
Raised intraocular pressure
Pigmented choroidal mass
Progressive asymmetry or new focal pigmentation

62. If a patient has a blue-grey facial patch but no ocular pigmentation, can you still diagnose nevus of Ota?

Yes. Ocular involvement is common but not mandatory for the cutaneous diagnosis. The term oculodermal melanocytosis is most appropriate when both skin and ocular structures are involved.

63. What is your final management plan for this patient?

Reassure that the lesion is benign.
Document with standardized clinical photographs.
Perform a full cutaneous and mucosal examination.
Arrange baseline ophthalmology assessment, including visual acuity, slit lamp, intraocular pressure, gonioscopy, and dilated fundus examination.
Advise annual ophthalmology follow-up, or more frequently if abnormalities are found.
Offer Q-switched or picosecond laser therapy if cosmetic treatment is desired.
Educate regarding warning signs of melanoma and glaucoma.
Biopsy only if there is a new suspicious nodule or atypical clinical change.

Examiner’s Closing Question: “What is the most important point in this case?”

Model answer:
“The most important point is that nevus of Ota is usually benign and cosmetically significant, but ocular involvement must always be assessed because of the risk of ipsilateral glaucoma and the small risk of uveal melanoma. Therefore, every patient should have baseline and periodic ophthalmological surveillance.”

Recent reviews continue to emphasize periodic eye follow-up and imaging-guided evaluation for ocular complications. The NCBI clinical review recommends baseline intraocular pressure assessment, gonioscopy, fundus examination, and ongoing surveillance.

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This is the patient for whom i need the description

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Nevus of Ota clinical description unilateral blue gray facial patch scleral pigmentation ophthalmic maxillary trigeminal distribution

Tailored Practical Case Description

This is a young adult female with a unilateral, asymptomatic facial hyperpigmented patch on the left side of the face.

On examination, there is a diffuse, ill-defined, mottled slate-grey to brownish-grey macular pigmentation involving the left frontotemporal region, upper and lower periorbital areas, malar region, and lateral cheek. The patch is flat, non-scaly, non-indurated, and without atrophy, ulceration, or surface textural change. There are areas of relatively deeper grey-blue pigmentation around the left eye and temple.

The distribution predominantly corresponds to the ophthalmic and maxillary divisions of the trigeminal nerve, namely V1 and V2. The lesion appears unilateral. There is no obvious nodularity or suspicious focal change in the photograph.

There appears to be pigmentation adjacent to the ocular surface; however, scleral or episcleral involvement cannot be confirmed reliably from this photograph alone. It should be specifically looked for on examination by slit lamp. Examine the conjunctiva, episclera/sclera, iris colour, angle, and fundus.

Provisional diagnosis:
Left-sided nevus of Ota, also known as oculodermal melanocytosis or nevus fuscoceruleus ophthalmomaxillaris.

Important practical note: The photograph also shows a few scattered small acneiform lesions and pigmentary macules. Do not call these part of the nevus of Ota. Describe the primary lesion separately as a flat, mottled dermal pigmentary patch.

How to Say It Before the Examiner

“On the left side of the face, there is a unilateral, ill-defined, non-scaly, non-indurated, mottled slate-grey to brownish-grey macular patch involving the frontotemporal, periorbital, and malar regions. The distribution is mainly in the ophthalmic and maxillary divisions of the trigeminal nerve. There is no nodularity, ulceration, or surface change. The clinical morphology is suggestive of nevus of Ota, or oculodermal melanocytosis. I would specifically examine for ipsilateral scleral or episcleral pigmentation and refer for ophthalmological assessment to exclude glaucoma and uveal melanocytosis.”

History to Elicit and Add to Your Presentation

Do not invent these details. Ask and then insert the actual answers:

Age at onset: “Was it present at birth, in childhood, or did it first appear around puberty?”
Course: “Has it progressively darkened or expanded?”
Symptoms: Usually asymptomatic. Ask about itching, pain, bleeding, visual blurring, headache, photopsia, or eye pain.
Hormonal change: “Did it darken during puberty, menstruation, pregnancy, or with oral contraceptive use?”
Past treatment: Laser, topical creams, chemical peels, or bleaching products.
Family history: Usually absent.
Ocular history: Reduced vision, raised intraocular pressure, glaucoma, or prior eye examination.
Mucosal or auditory symptoms: Tinnitus, hearing loss, or oral/nasal pigmentation.

If the lesion began in childhood and gradually deepened

Say:

“The lesion was first noticed in childhood and has gradually become darker over time, with no history of inflammation, trauma, drug intake, or preceding eruption. This supports nevus of Ota.”

Examination Points You Must Mention

Local examination

Colour: slate-grey, blue-grey, brownish-grey
Primary lesion: macules coalescing into a patch
Borders: ill-defined, irregular, mottled
Surface: smooth, no scale
Consistency: non-indurated
Hair: no hypertrichosis
Palpation: no tenderness, warmth, or sensory loss
Look for any papule, nodule, ulcer, or rapidly changing focus

Ocular examination

Say:

“I would inspect for ipsilateral conjunctival, episcleral, or scleral pigmentation, iris heterochromia or iris mammillations, and arrange slit-lamp examination, intraocular pressure measurement, gonioscopy, and dilated fundus examination.”

Nevus of Ota typically has blue-grey pigmentation in a unilateral V1-V2 distribution; ocular pigmentation may involve the conjunctiva, episclera, sclera, and uvea. NCBI clinical review

Mucosal and systemic examination

Look for:

Palate and buccal mucosa pigmentation
Nasal mucosa pigmentation
External auditory canal and tympanic membrane pigmentation
Lesions over shoulder and scapular area suggesting associated nevus of Ito
Port-wine stain or vascular malformation suggesting phakomatosis pigmentovascularis

Likely Examiner Questions Specific to This Patient

1. Describe the lesion.

“There is a unilateral, ill-defined, mottled, slate-grey to brownish-grey macular patch over the left frontotemporal, periorbital, malar, and lateral cheek region. It is flat and non-scaly, without induration, atrophy, ulceration, or nodularity.”

2. What is your diagnosis?

“Left-sided nevus of Ota, also called oculodermal melanocytosis.”

3. Why do you call it nevus of Ota?

“Because there is unilateral blue-grey to brown-grey facial dermal pigmentation around the orbit and malar region in the V1 and V2 trigeminal distribution. I would confirm or exclude ocular involvement by detailed ophthalmologic examination.”

4. Is ocular involvement visible in this picture?

“Not confidently. There may be periocular pigmentation, but scleral or episcleral pigmentation cannot be confirmed from a clinical photograph. I would examine it directly, preferably with slit lamp.”

This is a strong answer. Do not overstate that scleral pigmentation is present if you have not examined it.

5. What is the significance of ocular involvement?

“It establishes oculodermal melanocytosis and is important because of the increased risk of ipsilateral glaucoma and uveal melanoma.”

6. What is the most important investigation?

“Comprehensive ophthalmological assessment, including slit-lamp examination, intraocular pressure measurement, gonioscopy, and dilated fundus examination.”

7. Why measure intraocular pressure?

“Pigment deposition and abnormalities in the anterior chamber angle can obstruct aqueous outflow, producing secondary glaucoma, usually on the affected side.”

8. What is the risk of glaucoma?

“Approximately 10% is commonly quoted, though risk varies among series. Therefore, periodic ophthalmic surveillance is needed.”
Dermatology, 2-Volume Set, 5e, p. 2362.

9. What malignancy is associated?

“Uveal melanoma, particularly choroidal melanoma. Rarely, cutaneous, orbital, or meningeal melanoma can occur.”

10. Does this patient need a biopsy?

“Not routinely. The diagnosis is clinical. Biopsy is warranted only if there is diagnostic uncertainty or a new, raised, rapidly enlarging, irregular, ulcerated, or otherwise suspicious lesion.”

11. What histopathology would you expect?

“Scattered, elongated, dendritic, melanin-containing melanocytes between collagen bundles in the dermis, especially in the reticular dermis. There may be basal epidermal hyperpigmentation.”
Dermatology, 2-Volume Set, 5e, p. 2362.

12. Why is the lesion grey-blue?

“Because melanin is located in the dermis. The Tyndall effect makes deeply placed melanin appear blue-grey.”

13. Is it inherited?

“It is usually sporadic rather than hereditary, though rare familial cases are described.”

14. What is the expected course?

“It persists for life and can gradually become more extensive or darker, especially during periods of hormonal fluctuation such as puberty and pregnancy.”

15. What is the differential diagnosis in this patient?

Hori nevus or acquired bilateral nevus of Ota-like macules
Melasma
Lichen planus pigmentosus
Post-inflammatory hyperpigmentation
Blue nevus
Nevus of Ito
Mongolian spot, less likely due to location and persistence
Drug-induced pigmentation

16. How would you differentiate it from Hori nevus?

“Hori nevus is acquired, usually bilateral and symmetrical over the malar region, commonly affects adult women, and lacks ocular involvement. Nevus of Ota is usually unilateral, begins at birth or early life, involves V1-V2 territory, and may have scleral or other ocular pigmentation.”

17. How would you differentiate it from melasma?

“Melasma is typically bilateral and symmetrical brown hyperpigmentation over centrofacial or malar areas. It has no slate-blue dermal hue, no unilateral trigeminal distribution, and no ocular involvement.”

18. How would you differentiate it from lichen planus pigmentosus?

“Lichen planus pigmentosus presents with diffuse or reticulate grey-brown pigmentation, often photo-distributed or flexural, and may follow inflammation. It does not classically follow V1-V2 territory or involve ocular structures.”

19. What is treatment?

“Treatment is primarily cosmetic. Q-switched or picosecond pigment lasers are preferred. Options include Q-switched Nd:YAG 1064 nm, alexandrite 755 nm, and ruby 694 nm lasers.”

20. Why would you choose Q-switched Nd:YAG 1064 nm for this patient?

“It penetrates to the dermis and is relatively safer across darker skin types because it has lower epidermal melanin absorption than shorter-wavelength lasers. Multiple sessions are usually required.”

21. What must you counsel before laser treatment?

“Multiple sessions may be required; response is gradual; post-inflammatory hyperpigmentation or hypopigmentation can occur; strict photoprotection is needed; and laser treatment does not remove ocular melanoma or glaucoma risk, so ophthalmic follow-up remains necessary.”

22. What red flags would make you worry about malignant change?

“A new papule or nodule within the patch, rapid focal enlargement, variegated colour, ulceration, bleeding, persistent pain, visual symptoms, or a new pigmented ocular mass.”

Final Diagnosis Line for Your Record

Left-sided nevus of Ota (oculodermal melanocytosis), presenting as an ill-defined, mottled slate-grey to brownish-grey macular patch over the left V1-V2 facial distribution. Ocular involvement should be assessed clinically and by ophthalmology.

Do not describe this image as “classical scleral involvement” unless you have checked it directly. The safest exam wording is: “periocular involvement is present; ocular involvement needs evaluation.”

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