Abstract

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare T-cell lymphoma that primarily involves subcutaneous tissue with predilection for the lower extremities and younger patients. The diagnosis of SPTCL remains challenging to distinguish from other cutaneous lymphomas and reactive panniculitides.  Recent studies have suggested that germline mutations of HAVCR2 encoding Hepatitis A virus receptor 2 (also called T-cell immunoglobin mucin 3, TIM3) have been identified in patients with SPTCL and associated with severe hemophagocytic syndrome. However, no pathognomonic driver mutation has been identified yet. A retrospective review of available next generation sequencing data from 2019 to 2023 identified 8 cases of confirmed SPTCL. Within this cohort, two included evaluation for mutations in HAVCR2, which was identified in one of the two cases. Of the 8 total cases potentially pathogenic mutations were identified in HAVCR2 (1/8), DNMT3A (1/8), and RHOA (1/8). Variants of unknown significance were identified in PRDM1 (2/8), SETD2 (2/8), CREBBP (2/8), ARD11 (1/8), ETV6 (1/8), CEBPA (1/8), CSF1R (1/8), SPOCD1 (1/8), ZNF384 (1/8), CBL K477T (1/8), STX11 (1/8), CALR (1/8), PDGFRA (1/8), FYN (1/8), and SOCS1 (1/8). Our study expands the literature by contributing additional genetic mutations identified in SPTCL for diagnostic or therapeutic potential. Future studies will include testing on older cases to evaluate for HAVCR2.