Subcutaneous Panniculitis-Like T-Cell Lymphoma

T cell dyscrasias that demonstrate a proclivity for the subcutaneous fat include atypical lymphocytic lobular panniculitis, lupus profundus, and primary subcutaneous T cell lymphoma, including subcutaneous panniculitis-like T cell lymphoma (SPTCL). We encountered two patients who developed fever and indurated abdominal erythema at their peginterferon alfa-2a injection sites. Biopsies showed an atypical CD8 positive, granzyme positive, CD5 negative, MXA negative lymphocytic lobular panniculitis, diagnostic of SPTCL. Peginterferon alfa-2a was held in both patients. One patient received chemotherapy with an excellent response, while the other continued to have progressive disease. Peginterferon alfa-2a is known to significantly elevate serum MXA, which may induce high levels of MXA expression at the injection site, creating a microenvironment for the development of lupus profundus, which may eventuate into SPTCL. In summation, a potential risk of peginterferon alfa-2a injections is the development of SPTCL potentially arising in a background of an exogenous interferon triggered lymphocytic panniculitis.

The extranodal mature T-cell and NK-cell lymphomas and lymphoproliferative disorders represent a unique group of rare neoplasms with both overlapping and distinct clinicopathological, biological, and genomic features. Their predilection for specific sites, such as the gastrointestinal tract, aerodigestive tract, liver, spleen, and skin/soft tissues, underlies their classification. Recent genomic advances have furthered our understanding of the biology and pathogenesis of these diseases, which is critical for accurate diagnosis, prognostic assessment, and therapeutic decision-making. Here we review clinical, pathological, genomic, and biological features of the following extranodal mature T-cell and NK-cell lymphomas and lymphoproliferative disorders: primary intestinal T-cell and NK-cell neoplasms, hepatosplenic T-cell lymphoma, extranodal NK/T-cell lymphoma, nasal type, and subcutaneous panniculitis-like T-cell lymphoma.

While all peripheral T-cell lymphomas are uncommon, certain subtypes are truly rare, with less than a few hundred cases per year in the USA. There are often no dedicated clinical trials in these rare subtypes, and data are generally limited to case reports and retrospective case series. Therefore, clinical management is often based on this limited literature and extrapolation of data from the more common, nodal T-cell lymphomas in conjunction with personal experience. Nevertheless, thanks to tremendous pre-clinical efforts to understand these rare diseases, an increasing appreciation of the biological changes that underlie these entities is forming. In this review, we attempt to summarize the relevant literature regarding the initial management of certain rare subtypes, specifically subcutaneous panniculitis-like T-cell lymphoma, hepatosplenic T-cell lymphoma, intestinal T-cell lymphomas, and extranodal NK/T-cell lymphoma. While unequivocally established approaches in these diseases do not exist, we make cautious efforts to provide our approaches to clinical management when possible.