When a paraneoplastic lesion meets it’s maker-bilateral periocular skin and orbital collision of chronic lymphocytic leukaemia / small lymphocytic lymphoma (CLL/SLL) and necrobiotic xanthogranuloma (NBX) in the same biopsy

A 62-year-old female with known chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), without paraproteinemia and on no active CLL/SLL specific treatment, presented with bilateral proptosis, bilateral caruncle enlargement, and restricted eye movement associated with bilateral periocular and trunk skin yellowish non-ulcerated plaques. A magnetic resonance image scan (MRI) showed bilateral infiltration of all the extraocular muscles and intra-orbital fat with neck lymphadenopathy, suggesting lymphoma infiltration. Clinically, high-grade transformation of the CLL/SLL was suspected. One of the periocular skin and orbit lesions were biopsied for histology. These showed atypical lymphocytes, the morpho-immunohistochemical features of which confirmed CLL/SLL. No features of high-grade transformation were identified. Between the CLL/SLL nodules was a palisaded granulomatous lesion formed of necrobiotic collagen cuffed by swathes of variably xanthomatised CD163 positive histiocytes, with numerous multinucleated giant cells resembling Touton type giant cells. The features were those of a very unusual collision lesion of CLL/SLL and necrobiotic xanthogranuloma (NBX) in the same biopsy-a highly unusual occurrence.