Lymphomatoid Papulosis Misdiagnosed as Anaplastic Lymphoma

Lymphomatoid papulosis is a very rare skin disorder, defined as a chronic, recurrent, self-healing papulonodular or papulonecrotic skin eruption with suggestive histopathological features of a cutaneous lymphoma. We report a case of a 47-year-old male with an 8 years history of recurrent papulonodular lesions, some ulcerated, located on the face, trunk and extremities. The patient has been diagnosed primary with staphylococcal infection based on the clinical features and then, after a skin biopsy with anaplastic large cell lymphoma with CD30 positive cells and treated with CHOP. When he stopped the therapy, the lesions reappeared. A second skin biopsy was performed. Histological examination revealed an infiltrate of dyscohesive atypical lymphoid cells at the dermal-epidermal junction extending in the deep dermis. These atypical lymphoid cells varied in size and had pale abundant cytoplasm. Mitoses including atypical forms were prominent. Small mature appearing lymphocytes admixed with neutrophils and eosinophils were scattered throughout the tumor. Immunohistochemical studies demonstrated that the atypical lymphoid cells expressed CD30, Bcl-2 and Ki-67 (90%). Considering also the clinicopathological correlation, the morphological and immunohistochemical stains were suggestive for the diagnosis of lymphomatoid papulosis type A. Keywords: Lymphomatoid papulosis