Subcutaneous Leg Nodules

Abstract

The clinical differential diagnosis of subcutaneous leg nodules includes various types of (inflammatory) panniculitis, subcutaneous T-cell lymphoma, and infection. The panniculitides vary in their preference for sites of involvement (anterior versus posterior legs, overlying joints), whether they involute rapidly or persist for several weeks to a few months, whether they ulcerate or not, and history of apparent precipitating factors, or associated systemic disorders. Rarely, bacterial, atypical mycobacterial and systemic fungal infection may present with deep dermal and subcutaneous nodules that may be mistaken clinically for inflammatory panniculitis.

In the workup of patients with leg nodules, any combination of the following may be needed to arrive at an accurate diagnosis: adequate biopsy, special stains, immunohistochemistry, molecular testing for TCR clonality, and evaluation for systemic disorders.