Abstract:

Mycosis fungoides has previously been reported in invisible form, when biopsy of normal-appearing skin in the background of undifferentiated chronic pruritus demonstrated the malignancy. Asymptomatic cases have been reported more infrequently on biopsies of individual skin lesions. Here we report the first case of asymptomatic and invisible mycosis fungoides identified on wide local excision of a cutaneous neoplasm. A 61-year-old woman underwent wide local excision for a dysplastic nevus of the upper back. She had previously complained of generalized xerosis and a scaly patch on the right forearm present for two years, but had not previously been diagnosed with mycosis fungoides. Her past medical history included melanoma in situ on the cheek, systemic lupus erythematosus, renal transplantation with ongoing immunosuppression, and monoclonal gammopathy of undetermined significance. No residual melanocytic neoplasm was identified on the curative excision of the dysplastic nevus site; however on the lateral margins of the specimen an epidermotropic infiltrate of atypical lymphocytes exhibiting cerebriform morphology and Pautrier microabscesses were identified. Immunohistochemical stains demonstrated the presence of CD3+, CD4+, and CD5+ lymphocytes, with significant reduction in CD7 and CD8 expression. The epidermal lymphocytes were CD20-. Additional biopsies were subsequently performed of the scaly patch on the right arm. A similar pattern of atypical lymphocytes and immunohistochemical staining confirmed the diagnosis of mycosis fungoides. Pruritus is a common manifestation of mycosis fungoides, and the relationship between hematologic malignancy and pruritus is well-established. Albeit rare, biopsy specimens taken for undifferentiated pruritus should raise a high suspicion for mycosis fungoides. Our case highlights the importance of thorough examination of all tissue specimens, as the diagnosis allowed for the patient to be treated early in the disease course.

Financial Disclosure:
No current or relevant financial relationships exist.

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Kristopher Peters