Abstract
Xeroderma pigmentosum type C (XP-C) is a rare autosomal recessive disorder that predisposes patients to skin cancers including squamous cell carcinoma and melanoma due to their inability to repair DNA damage caused by ultraviolet radiation. Here, we present an unusual case of the rapid development of multifocal primary cutaneous diffuse large B cell lymphoma (PCLBCL) on the left medial thigh and right lateral neck of a 37-year-old male with an underlying diagnosis of XP-C. Microscopic examination of both nodules revealed pan-dermal infiltrates composed of large, atypical lymphocytes with numerous mitotic figures. Foci of necrosis were prominent. Immunohistochemical studies were notable for strong positive staining for CD20, CD79a, BCL-2 and MUM-1, with patchy and weak positivity for BCL-6 and a high proliferative index with Ki-67. Molecular studies showed no re-arrangements for MYC, BCL6, and BCL2 genes. The patient was referred to medical oncology for further management. Workup including a PET-CT revealed hypermetabolic subcutaneous masses on the right shoulder and left medial thigh, right cervical and left axillary lymphadenopathy, and subcapsular hepatic lesions suspicious for systemic involvement. The patient was started on R-CHOP chemotherapy with clinical response following the first cycle. The association between XP-C and the development of PCLBCL is not well understood; however, one case series reported a possible increased incidence of lymphoma, including PCBCLs, in patients with XP-C1. This case highlights the importance of considering lymphoma as a potential diagnosis in patients with XP-C and cutaneous lesions.
