Abstract

We report a case of a 67-year-old female with a history of systemic lupus erythematosus who presented with multiple depressed plaques of the upper arms that were refractory to treatment. Histologic examination of the punch biopsy of the right upper arm revealed a lymphocytic panniculitis with small-to-medium size lymphocytes rimming the adipocytes and infiltrating through the adipose tissue. Karyorrhexis and “beanbag”-like cells were seen. Immunohistochemical analysis revealed the atypical lymphocytes to be T-cells, exhibiting CD3 positivity and a slight predominance of CD4 over CD8. TIA was diffusely expressed while definitive CD8 rimming was not prominent. A Ki-67 highlighted multiple hotspots and clusters of staining cells (50-60%). The elevated Ki-67, hot spots, and prominent lymphocytic rimming in conjunction with no treatment response raised concern for a diagnosis of subcutaneous panniculitis-like T-cell lymphoma (SPTCL). A second biopsy of a separate lesion showed classic features of lupus panniculitis. T-cell gene rearrangement testing was performed which was negative for T-cell clonality, favoring a diagnosis of lupus panniculitis with atypical features. Given the problematic overlap of histopathologic features between lupus panniculitis and SPTCL and the risk of mistreatment, it is important to correlate a thorough diagnostic workup with the clinical picture when encountering atypical lymphocytic panniculitides.

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