Hair Pull Test (Sabouraud Maneuver)

Technique

The test is performed in a patient who has not shampooed for more than 24 hours prior to examination. The examiner grasps approximately 40-60 hairs between the thumb, index, and middle fingers from the base near the scalp and pulls firmly - but not forcefully - along the hair shafts. The process is repeated in at least 3 scalp areas: frontal, occipital, and temporal regions.

Fitzpatrick's Dermatology, Vol. 1-2

Interpretation

Finding	Interpretation
>10% of grasped hairs extracted (strict criterion)	Positive - active shedding
>5-6 hairs consistently from 2+ areas (clinical criterion)	Positive - probable effluvium
Diffusely positive across all regions	Telogen effluvium
Positive in frontal region, negative in occipital	Androgenetic alopecia (AGA)
Strongly positive	Alopecia areata incognita
Negative	Does NOT exclude telogen effluvium

Root Morphology of Extracted Hairs (Critical Step)

After collecting hairs, examine root morphology - this distinguishes the cause:

Club-shaped (telogen) roots - blunt, white, pigment-free bulbs with an intact root sheath. Seen in telogen effluvium. (See figure below)
Tapered "pencil point" roots (dystrophic anagen) - strongly suggests alopecia areata
Anagen roots - soft, pigmented, irregularly shaped bulbs with a root sheath; pulled in anagen effluvium (e.g., chemotherapy)

Telogen club hairs with intact hair roots collected by hair pull test - Fitzpatrick's Dermatology, Fig. 86-5

Clinical Correlations by Diagnosis

Diagnosis	Hair Pull Test Result
Telogen effluvium (TE)	Diffusely positive; telogen club hairs extracted
Alopecia areata	Positive at margins of patch; tapered anagen hairs
Alopecia areata incognita	Strongly positive (diffuse, no visible patches)
AGA (androgenetic alopecia)	May be positive frontally; negative occipitally
Female pattern hair loss	Usually not valuable for distinction from chronic TE
Protein-energy malnutrition	Positive gentle hair pull

Comparison with Trichogram

The trichogram is the more formal, semi-invasive version of the hair pull test - forceps are used to pluck 50-100 hairs, which are then examined microscopically for the telogen:anagen ratio. Acute TE is suggested if the telogen rate exceeds 25% (normal telogen rate ~13%). The hair pull test is a simpler bedside screen, but the trichogram gives quantitative cycle data.

Key Limitations

A negative test does not exclude telogen effluvium
The "normal" daily hair loss count is not firmly standardized (range 40-180 hairs/day in studies; >100/day is widely used as a threshold for abnormal)
The test can be positive in multiple conditions, so root morphology examination is essential to differentiate them

- Fitzpatrick's Dermatology, Vol. 1-2 (Chapter 86)

Corn vs callus

Finding Sources

Reading File

Corn vs. Callus

Both are forms of hyperkeratosis caused by repeated mechanical pressure or friction, but they differ structurally, anatomically, and clinically.

Comparison Table

Feature	Callus (Tyloma)	Corn (Clavus)
Latin name	Callus / Tyloma	Clavus
Shape	Diffuse, broad, flat thickening	Circumscribed, conical
Central core	Absent	Present - hard, horny core pointing inward
Pain	Usually painless (unless severe)	Painful - core presses on sensory nerves (dull/boring or sharp/lancinating)
Location	Palms, soles, bony prominences, weight-bearing areas	Dorsa of toes (hard corn), interdigital spaces (soft corn), soles
Surface	Diffuse yellowish thickening	Shiny, polished surface; core visible on paring
Disappears with pressure removal	Yes	Yes
Bony abnormality underneath	Uncommon	Common (exostosis or bony spur, especially in longstanding cases)

Andrews' Diseases of the Skin, p. 52

Callus

A callus is a non-penetrating, circumscribed hyperkeratosis - it has no central core and represents a more diffuse skin thickening. It arises wherever repetitive pressure is applied: palms, soles, bony joint prominences. It tends to disappear spontaneously when the causative pressure is removed.

Notable occupational/activity calluses include: boxer's knuckle pads, surfer's nodules, tennis toe, rower's rump, violinist's neck callosity, and Russell sign (calluses on the dorsum of the hand over the MCP/IP joints - a clue to bulimia nervosa).

Corn (Clavus)

Corns are circumscribed horny conical thickenings with the base on the surface and the apex pointing inward, pressing on underlying sensory nerves. There are two types:

Hard Corn (Heloma Durum)

Located on the dorsa of toes or subungually/soles
Shiny, polished surface
Paring reveals a clear, hard central core
Pain is dull/boring or sharp/lancinating from core pressure on nerves

Soft Corn (Heloma Molle)

Located in interdigital spaces (most commonly the 4th web space)
Softened and macerated by sweat - appears white and soggy
Caused by bony pressure between adjacent toes (e.g., medial flare of the 5th toe's distal phalanx pressing on the 4th toe's IP joint)
Can ulcerate and become infected

Corn vs. Plantar Wart (Important Differential)

Maneuver	Corn	Plantar Wart
Lateral squeeze	Painless	Painful
Perpendicular pressure	Painful	Less painful
On paring	Clear horny core	Elongated dermal papillae with punctate bleeding vessels

Treatment

Callus:

Padding to relieve pressure
Paring/pumice stone
Keratolytics: 40% salicylic acid plasters, 12% ammonium lactate lotion, urea-containing cream
Corrective footwear

Corn:

Pressure relief (ring of soft felt wadding, corrective footwear)
Soaking + paring the surface, especially removing the central core
40% salicylic acid plaster (reapply every 48 hours after paring)
Er:YAG laser ablation
Punch excision
If underlying bony exostosis: surgical removal is often necessary for definitive cure; simple surface treatments will fail without addressing the bony cause

- Andrews' Diseases of the Skin, p. 52; Campbell's Operative Orthopaedics 15th Ed 2026

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