Primary cutaneous anaplastic large cell lymphoma occurring in an atopic dermatitis patient: a case report with review of the literature with emphasis on their association.

Although the risk of malignant lymphoma in patients with atopic dermatitis (AD) remains controversial, an increased risk of malignant T-cell lymphoma in patients with AD has been reported. Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is a relatively common distinct clinicopathological entity. However, occurrence of C-ALCL in patients with AD has been rarely reported. Herein, we describe the 5(th) reported case of C-ALCL occurring in a patient with AD and review the clinicopathological features. A 30-year-old Japanese male with a long-standing history of AD presented with a gradually enlarged nodular lesion in the right abdominal wall, which had spontaneously regressed without therapy. Two years later, multiple nodular lesions appeared in his trunk, and swelling of multiple lymph nodes was also detected. Histopathological studies demonstrated diffuse proliferation of large-sized lymphocytes with large convoluted nuclei containing conspicuous nucleoli and relatively rich cytoplasm in the skin and lymph node. Immunohistochemically, these lymphocytes were positive for CD30, CD8, and MUM1, and negative for CD3, CD4, and ALK1. Accordingly, a diagnosis of primary C-ALCL was made. The patient died of disease after various courses of chemotherapy. Our clinicopathological review revealed that the prognosis of C-ALCL occurring in patients with AD is poor because two of 5 patients died of disease. Therefore, albeit extremely rare, AD patients with C-ALCL should be monitored closely, and additional clinicopathological studies are needed to clarify the pathogenesis of C-ALCL occurring in patients with AD.