Lupus Vulgaris (Tuberculosis Luposa)

What is Lupus Vulgaris?

Epidemiology

• Females are affected 2-3 times more often than males
• All age groups affected equally
• Less common in the United States than in Europe
• Incidence has declined steadily worldwide

Clinical Features

• Location: ~90% involve the head and neck - commonly starts on the nose, cheek, earlobe, or scalp
• Initial lesion: brownish-red, soft or friable macule or papule (smooth or hyperkeratotic surface)
• Pathognomonic sign: "Apple jelly" color on diascopy (pressing a glass slide on the lesion reveals a yellowish-brown translucent color - the hallmark of LV)
• Progression: elevation, deeper brownish color, plaque formation; gyrate outline due to involution in one area with expansion in another
• Small soft papules called "lupomas" are embedded deeply and diffusely in the infiltrated dermis
• Ulceration may occur; mucosae can be primarily involved
• Postexanthematic lupus: after measles (or other febrile illness), multiple disseminated lesions may arise from hematogenous spread - Andrews' Diseases of the Skin, p. 383

Histopathology

• Prominent tubercle formation (epithelioid granulomas) - the most characteristic feature
• Secondary changes: epidermal thinning/atrophy, acanthosis, pseudoepitheliomatous hyperplasia
• Acid-fast bacilli are usually NOT found (paucibacillary nature)
• Old lesions composed mostly of epithelioid cells - may be impossible to distinguish from sarcoidosis

Diagnosis

Differential Diagnosis

• Also: Colloid milia, acne vulgaris, rosacea, chronic discoid lupus erythematosus, Hansen disease

Complications

• Cartilage destruction of nose or ear - extensive disfigurement
• Atrophic scarring (characteristic - may recur within a scar)
• Fibrosis - can be pronounced and mutilating
• Dry rhinitis, destruction of nasal septum cartilage
• Scarring of soft palate, laryngeal stenosis
• Malignant transformation: long-standing LV can lead to squamous cell carcinoma (SCC outnumbers BCC; high risk of metastases)
• 40% of patients: associated TB lymphadenitis
• 10-20%: active pulmonary TB or TB of bones/joints
• Pulmonary TB is 4-10 times more frequent in LV patients vs. the general population

Treatment

• Standard 4-drug regimen: Isoniazid + Rifampicin + Pyrazinamide + Ethambutol for 2 months, then Isoniazid + Rifampicin for 4 months (total 6 months)
• Without therapy, the disease progresses over many years to functional impairment and disfiguration
• Complete healing rarely occurs without therapy, though spontaneous involution of some lesions is possible

Hair Loss (Alopecia)

Classification Overview

1. Androgenetic Alopecia (Pattern Hair Loss)

Male Pattern

• Begins in teens, 20s, or early 30s; starts with bitemporal recession ("professor angles") and vertex thinning
• Driven by dihydrotestosterone (DHT) - 5α-reductase converts testosterone to DHT, which miniaturizes follicles
• Each hair cycle produces finer, shorter hairs; terminal hairs are replaced by vellus hairs
• Progressive shortening of anagen phase; parietal and occipital areas typically spared

Female Pattern

• Diffuse thinning throughout the apical scalp; frontal hairline usually preserved
• Same follicular miniaturization and DHT mechanism as males, though less pronounced
• Always consider underlying androgen excess (PCOS, ovarian/adrenal tumor) if signs of virilization exist

Pathogenesis

• Polygenic inheritance with androgen sensitivity
• Higher 5α-reductase and androgen receptor levels in frontal vs. occipital follicles
• Androgen-inducible TGF-β1 from dermal papilla cells suppresses hair growth
• Eunuchs do not develop baldness - confirms androgen dependence

Treatment

2. Alopecia Areata (AA)

Variants

• Patchy AA - circumscribed patches (most common)
• Alopecia totalis - complete loss of scalp hair
• Alopecia universalis - complete loss of all body hair

Pathogenesis

• Loss of immune privilege of the hair follicle - normally, follicles express low MHC Class I/II and produce local immunosuppressive cytokines
• CD8+ cytotoxic T cells (supported by IL-15 and IFN-γ) attack anagen hair bulbs, inducing premature catagen transition
• Since only the bulb is attacked (not the stem cell-containing bulge), regrowth is possible - classic non-scarring pattern
• Associated with other autoimmune diseases: thyroiditis, vitiligo, atopic dermatitis
• Fitzpatrick's Dermatology, p. 229

Clinical Features

• Well-demarcated, smooth, circular bald patches
• "Exclamation mark hairs" - broken, tapered hairs at patch margin
• Scalp biopsy: lymphocyte-predominant inflammation around anagen bulbs

Treatment

• Intralesional corticosteroids (triamcinolone acetonide) - first-line for limited disease
• Topical/systemic corticosteroids - for more extensive disease
• JAK inhibitors (baricitinib, ritlecitinib) - FDA-approved for severe AA; block JAK-STAT signaling, suppress inflammatory T cells, and directly promote hair follicle growth
• Topical minoxidil (adjunct)
• Spontaneous regrowth occurs in ~50% of patchy AA cases

3. Telogen Effluvium (TE)

Mechanism

• Premature termination of the anagen (growth) phase of hair follicles → increased proportion in telogen (rest) phase → excessive shedding of club hairs (hairs with depigmented, club-shaped bulb, no sheath)
• Hair loss typically occurs 2-4 months after the triggering event

Common Triggers

• Fever / systemic illness
• Childbirth (postpartum effluvium) - most common type in women
• Major surgery or trauma
• Emotional stress
• Rapid weight loss / crash dieting
• Iron deficiency
• Hypothyroidism / hyperthyroidism
• Drugs (heparin, warfarin, propylthiouracil, isotretinoin, lithium, beta-blockers, interferons, colchicine, amphetamines)
• Chemotherapy (anagen effluvium - even more abrupt)

Types

Diagnosis

• Pull test: grasp 40 hairs, slow pull - >4-6 club hairs is abnormal
• Shed hairs show depigmented club-shaped bulb (vs. anagen hairs which have pigmented bulb + sheath)
• Normal scalp has ~100,000 hairs; normal daily loss 100-150; in TE, 150-400+ shed daily

Treatment

• Identify and remove the trigger - spontaneous recovery is expected in most acute cases
• No specific therapy usually required; full recovery once the cause is corrected
• Andrews' Diseases of the Skin, p. 870

4. Scarring Alopecias

5. Other Causes of Hair Loss

Diagnostic Approach Summary

1. Scarring vs. non-scarring - look for follicular openings on scalp
2. Pattern - diffuse vs. patchy vs. patterned
3. Pull test - assess telogen shed
4. History - triggering events 2-4 months prior, medications, systemic symptoms
5. Labs - TSH, ferritin, CBC, androgens (in women with virilization)
6. Scalp biopsy - gold standard for scarring alopecias and diagnostic uncertainty
7. Dermoscopy/trichoscopy - non-invasive assessment of follicular miniaturization, exclamation mark hairs, etc.

Radiological Changes in Psoriasis (Psoriatic Arthritis)

P - Pencil in Cup Deformity O - Osteolysis I - Ivory Phalanx S - Sausage Digits O - Opera Glass Deformity N - Narrowing of Joint Spaces

Detailed Breakdown of Each Finding

1. Pencil-in-Cup Deformity

• The most pathognomonic radiological finding of psoriatic arthritis
• Erosions on the distal side of the DIP joint cause the head of the bone to become tapered and pointed ("pencil"), while the base of the next phalanx becomes eroded and widened into a cup shape
• The tapering/whittling of the phalanges with cupping of the proximal end is what creates the classic pencil-in-cup appearance
• Seen at DIP and PIP joints of both hands and feet
• "Erosions on the distal side of the joint classically merge together to produce a 'pencil-in-cup' appearance considered by some to be pathognomonic of the disease" - Grainger & Allison's Diagnostic Radiology

2. Osteolysis

• Acro-osteolysis: resorption/destruction of the distal phalangeal tufts - a hallmark feature
• Helps distinguish PsA from erosive osteoarthritis
• Progressive osteolysis of terminal phalanges gives them a peg-like appearance
• May progress to involve most or all of a phalanx
• Osteolysis of metatarsals also occurs

3. Ivory Phalanx

• Increased density (sclerosis) of a phalanx, giving it a uniformly dense, white "ivory" appearance on X-ray
• Due to periosteal new bone formation and sclerosis
• A unique feature of psoriatic arthritis not seen in RA
• Most commonly seen in the terminal phalanx

4. Sausage Digits (Dactylitis)

• Global uniform swelling of an entire digit from tip to base
• Caused by enthesitis at multiple sites within the digit plus tenosynovitis of the flexor tendon sheath
• Clinically: the whole finger/toe looks like a sausage
• Radiologically: diffuse soft-tissue swelling of the whole digit
• "Global swelling of a digit in the form of dactylitis or the so called 'sausage digit' is typical" - Grainger & Allison

5. Opera Glass Deformity (Arthritis Mutilans)

• Seen in the most severe destructive form of PsA - arthritis mutilans (~5% of patients)
• Severe osteolysis of phalanges and metacarpals causes shortening and telescoping of digits
• The skin wrinkles and folds as the bone collapses inward - resembles a collapsible opera glass/telescope
• Clinically, the digit can be pulled out to normal length ("telescoping" or "main en lorgnette")
• "Typically involving multiple digits, this rare arthropathy has been termed arthritis mutilans or the opera glass hand" - Firestein & Kelley's Rheumatology

6. Narrowing of Joint Spaces

• Due to cartilage destruction from synovial inflammation
• Involves DIP and PIP joints preferentially; relative sparing of MCP and MTP joints (helps distinguish from RA)
• May progress to bony ankylosis (complete fusion) - another feature distinguishing PsA from RA
• Note: periarticular osteopenia is characteristically absent in PsA (unlike RA where it is prominent) - this is a key distinguishing feature

Other Notable Radiological Features of PsA

Clinical Patterns of PsA (5 Types)

• HLA-B27 positive in ~50% of patients
• Skin involvement precedes joint disease by several years

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Radiology Images - Psoriatic Arthritis (POISON)

🔴 Image 1 - Pencil-in-Cup Deformity + Osteolysis (DIP Joints, Fingers)

🔴 Image 2 - DIP Erosion + Enthesophyte Formation

• Arrows = erosion of the distal phalanx at the joint margins
• Asterisks = prominent fluffy enthesophyte (new bone) formation both proximal and distal to the DIP joint
• This "bone erosion + new bone formation" combination is characteristic of PsA (unlike RA which shows pure erosion)

🔴 Image 3 - Arthritis Mutilans / Opera Glass Deformity (Foot, MTP Joints)

• Subluxation and complete erosion/loss of the phalanges at the MTP joints
• The 4th toe shows nearly complete dissolution of the middle and distal phalanges - severe osteolysis
• This extreme bone destruction leads to the opera glass / arthritis mutilans appearance clinically

🔴 Image 4 - Psoriatic Spondylitis + Asymmetric Sacroiliitis (Spine)

• Arrows = Asymmetric sacroiliitis (unilateral/asymmetric joint space loss on the left - distinguishes PsA from AS which is symmetric)
• Asterisks = Spinal enthesophytes that are coarse and more horizontally oriented (compared to the fine, vertically oriented syndesmophytes of ankylosing spondylitis)
• No "bamboo spine" (complete fusion) - that is more characteristic of AS

Summary: What Each Image Shows