Generalized early inflammatory morphea mimicking interstitial T‐cell lymphoma: A diagnostic pitfall

Early generalized morphea can clinically mimic mycosis fungoides. The microscopic features of early inflammatory morphea may show variable degrees of infiltration and do not have the characteristic dermal collagen sclerosis. We report the case of a 63-year-old female patient who presented with a 2-month history of an asymptomatic skin rash. Physical examination revealed multiple erythematous to dusky patches on the trunk and thighs, resembling the patch stage of mycosis fungoides. Two skin biopsies were performed, both of which showed prominent interstitial lymphoid infiltration in the reticular dermis without dermal sclerosis. Small lymphocyte exocytosis and lining along the dermal-epidermal junction were observed focally in the epidermis. Small clusters of plasma cells and eosinophils were observed in perivascular areas. Although no predominant clonality was found for CD4 and CD8 stains, 50% loss of CD5 antigen and 90% loss of CD7 antigen expression were apparent in immunohistochemical studies. Subsequent blood tests showed a normal blood cell count and positive human T-lymphotropic virus Type 1 antibodies. The overall findings suggested interstitial mycosis fungoides or early adult T-cell lymphoma-leukemia. The patient refused aggressive treatment, and 3 months later, she presented with indurated plaques from the previous rash. A repeat biopsy revealed the typical features of morphea. This report discussed the pitfalls in the clinical and histopathological diagnosis of early generalized inflammatory morphea that both clinicians and pathologists should consider.