From the Journals

Rare epidermotropic MZL yields to rituximab



Epidermotropic marginal zone lymphoma (MZL), a rare cutaneous B-cell lymphoma identified in only eight patients to date, appears to be responsive to rituximab, according to authors of a case report.

A 69-year-old man who presented with a generalized papulosquamous eruption that was eventually diagnosed as epidermotropic MZL achieved a near total remission within 3 months of receiving four total weekly rituximab infusions, reported Cynthia M. Magro, MD, from Cornell University, New York, and her colleagues from the University of Arizona, Tucson (JAAD Case Rep. 2017 Sep 23;3[6]:474-6).

“Epidermotropic MZL represents a distinctive nosologic B-cell lymphoma that should be considered a diagnostic possibility in older men who present with an unexplained papulosquamous eruption resembling pityriasis rosea,” the researchers wrote.

“Epidermotropism refers to a state of abnormal colonization of the epidermis by leukocytes, which often reflects a clonal T-cell or monocyte dyscrasia. Epidermotropism is a distinctive pattern of passive migration into epithelial structures that is not otherwise attributable to the normal function of innate and adaptive immunity,” the researchers explained.

They described the case of the aforementioned patient, who presented with asymptomatic indurated, red-to-brown papules and plaques on his chest, abdomen, back, and buttocks, which gave the clinical impression of pityriasis rosea or a similarly appearing drug reaction.

Histopathologic examination of two biopsied lesions “demonstrated a dense superficial lymphocytic infiltrate that expanded and effaced the papillary and superficial reticular dermis.”

After epidermotropic MZL was diagnosed, the patient was evaluated for systemic disease with a bone marrow biopsy, which revealed a low-grade B-cell lymphoproliferative disorder, and with a PET scan showing lymphomatous infiltration of the spleen. The patient was treated with four weekly infusions of rituximab 375 mg/m2.

“Within 3 months, he experienced marked regression of his cutaneous disease. Repeat radiographic imaging found an interval decrease in the size of his spleen, signifying an objective response. Since achieving near total clinical remission, the patient remains under the close observation of medical oncology services,” the researchers wrote.

The investigators noted that if histopathology is the only method used to diagnosis the condition, epidermotropic MZL could be mistaken for a T-cell lymphoproliferative disorder, such as mycosis fungoides, because of the similar architecture at low resolution.

“In these settings, immunohistochemical staining for B-cell markers represents an indispensable diagnostic test,” they wrote.

The researchers reported having no conflicts of interest.