Extracutaneous involvement of subcutaneous panniculitis-like T-cell lymphoma associated with hemophagocytic lymphohistiocytosis and refractory to intensive chemotherapy

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon primary cutaneous lymphoma characterized by subcutaneous infiltration of mature cytotoxic T-cells with rearranged alpha/beta T-cell receptor phenotype. SPTCL is typically a disease of young adults with 36 years old being the median age. Patients commonly present with B-symptoms and multiple painless skin nodules in the extremities and trunk. Extracutaneous involvement is rare. Here, we present a case of SPTCL in a 32-year-old woman with diffuse but clinically occult skin lesions detected on imaging through multiple modalities and pathology-proven extracutaneous involvement in the mesentery. Retrospective chart review, review of patient specimens, and literature review for similar cases were performed. Histologic examination revealed SPTCL in the skin and omentum. Our patient’s clinical course was associated with hemophagocytic lymphohistiocytosis (HLH), a known poor prognostic indicator, and refractoriness to intensive chemotherapy. Due to the rarity of this disease, treatment is not yet standardized. However, for our patient, an allogeneic stem-cell transplant resulted in positron emission tomography/computed tomography-negative remission 11 months post-transplant or 20 months post-initial presentation. We report an unusual case of subcutaneous panniculitis-like T-cell lymphoma (SPTCL) with clinically occult subcutaneous lesions and prominent biopsy-proven extracutaneous mesenteric involvement. Further investigation is required to better understand the mechanism of disease, prognosis, and optimal treatment approach for SPTCL patients presenting with extracutaneous involvement and HLH.