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Journal of the American Academy of Physician Assistants:
Dermatology Digest

A lesion on the bottom of the foot

SHARMA, MALVEEKA MPH; EHRSAM, ERIC MD; KHACHEMOUNE, AMOR MD, FAAD

Section Editor(s): Monroe, Joe R. PA‐C, MPAS

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department editor

Malveeka Sharma is a third‐year student at the University of South Florida, Morsani College of Medicine, Tampa. Eric Ehrsam is a dermatologist in private practice in Lille, France. amor Khachemoune is a Mohs surgeon and dermatopathologist at the Veterans Affairs Medical Center, Brooklyn, New York.

No relationships to disclose.

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>CASE

An 18‐year‐old male presented to the dermatology clinic for evaluation of a pigmented lesion on the sole at the base of the metatarsal area (Figure 1). The asymptomatic lesion had been present for the past 3 months.

Figure 1
Figure 1
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>WHAT IS THE MOST LIKELY DIAGNOSIS?

* Terra firma‐forme dermatosis

* Verruca plantaris

* Talon noir

* Melanoma not otherwise specified

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>DISCUSSION

The diagnosis was talon noir, a benign dermatologic condition produced secondary to trauma. The lesion is characterized by minute hemorrhaging into the upper layer of skin. Talon noir was first described in 1961 in 16 athletes.1 Many of the benign lesions were misdiagnosed as plantar warts and malignant melanoma. Talon noir has also been known as black heel, calcaneal petechiae, and posttraumatic cutaneous intracorneal bleed.

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Clinical presentation

Classically, talon noir is preceded by sports activities that involve running on hard surfaces, stopping quickly, and pivoting, such as basketball, tennis, running, gymnastics, and volleyball. The proposed mechanism is shearing forces on the foot that lead to tearing of capillaries in the papillary dermal layer. The lesions are most commonly located on the posterior heel at the convex aspect where the fat pad is thinnest.

A number of other traumatic causes leading to identical histopathologic findings of talon noir are found in varying locations. These causes include burns with hot sand, friction against rough edges, and wearing of new shoes. A similar lesion known as black palm has been found on the thenar eminence of the palms of golfers, weight lifters, and climbers. Recently, an increasing number of cases of so‐called PlayStation thumb have been described, mostly in adolescents who play video games excessively.

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Histology/dermatoscopy

The his tology of talon noir demonstrates hyper keratosis and epidermal acanthosis within the epidermal area. Both focal hemorrhage and hemorrhaging in pools are observed within the stratum corneum. Shavings of the lesion can be stained with benzidine, which stains erythrocytes that have bled from vessels in the papillary dermis. Focal deposits of coagulated blood are visible in the horny layer, typically in a circular pattern composed of eosinophils and amorphous material.

The characteristic dermatoscopic description of talon noir is that of redblack pigmentation with disconnected peripheral satellite red‐black globules coalescing in a linear form. The lesion is found superficially in the horny layer.

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Differential diagnosis

Talon noir is often misclassified as melanoma. However, melanoma is not usually preceded by trauma, and it is characterized histologically by atypical melanocytes that are highly associated with a desmoplastic response. Verruca plantaris is a cauliflowerlike lesion with small black petechiae found on the sole of the foot. The histology demonstrates focal hemorrhaging over papillary projections, resulting in a caplike hemorrhage appearance. Terra firma‐forme dermatosis is found on a neglected area of skin. There are no histologic findings, as this is a superficial accumulation of sebum, keratin, or dirt.

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Management

Talon noir is a benign, asymptomatic lesion that is self‐limited. Preventive measures include avoiding the sport or traumatic event that led to the lesion; using a gel‐type foot pad; and wearing shoes that have been properly fitted, especially air‐ or gelcushioned athletic shoes for sports.

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REFERENCE

1. Crissey JT, Peachy JC. Calcaneal petechiae. Arch Dermatol. 1961;83:501.

© 2012 Lippincott Williams & Wilkins, Inc.

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