Primary Marginal Zone Lymphoma of the Subcutis Associated With Panniculitis and Fat Necrosis.

Abstract

Lymphocytic infiltrates in the subcutaneous adipose tissue, often accompanied by fat necrosis, are typically seen in benign panniculitis. Diagnostic considerations include subcutaneous panniculitis-like T-cell lymphoma and cutaneous γδ T-cell lymphoma, whereas a primary subcutaneous B-cell lymphoma in this setting has not been previously described. We report the case of a 72-year-old woman with multiple deep cutaneous nodules on the trunk and upper extremities. During 3 years of clinical follow-up, new skin nodules developed, while existing lesions remained stable or regressed. No other organ involvement was detected. Sequential biopsy specimens of the subcutaneous lesions revealed patchy, predominantly septal, lymphocytic infiltrates associated with extensive hyaline fat necrosis. The histologic and immunophenotypic features were consistent with marginal zone lymphoma. Genotyping revealed an identical monoclonal immunoglobulin gene rearrangement across all biopsy specimens. This case represents, to our knowledge, the first reported case of primary subcutaneous B-cell lymphoma closely associated with panniculitis.