Abstract

A 63-year-old African American man presented with a new pruritic rash that had been “coming and going” for about 2 months prior to presentation. Of note, he had been diagnosed with nasopharyngeal mantle cell lymphoma 1 month prior and recently began chemotherapy with bendmustine and rituximab. Exam revealed serpiginous erythematous plaques with fine scale and a “wood grain” leading edge. Present on the bilateral axilla and antecubital fossa, the differential diagnosis of the rash included the paraneoplastic eruption of erythema gyratum repens (EGR) versus an unusual presentation of tinea corporis. EGR is an uncommon dermatosis characterized by marble-like swirls of erythema and slightly raised serpiginous bands resembling wood grain. This rare dermatosis is typically associated with underlying malignancy and often precedes the diagnosis of cancer by several months. Despite its distinctive presentation, it is important for clinicians to consider other common dermatologic conditions that may share similarities with EGR, such as tinea corporis. A biopsy showed PAS positive fungal hyphae in the stratum corneum, thus establishing a diagnosis of tinea. Awareness of dermatologic manifestations in various skin tones, especially in skin of color, is an important aspect of providing exceptional medical care. While it is crucial to take into consideration a significant past medical history, such as the history of mantle cell lymphoma in our patient, to develop a differential diagnosis, clinicians must always keep in mind that a horse can be disguised as a zebra – a common dermatologic condition can mimic a rare disease. Recognizing the variations in clinical manifestations of disease and appropriate use of skin biopsy prevents misdiagnosis, and ultimately results in optimal patient management.

Financial Disclosure:
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