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To the editor,
Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin's lymphoma (NHL) and displays heterogeneity. The precise mechanisms of lymphomagenesis are unknown; however, there is evidence that genetic instability arising from somatic hypermutation plays a role.1 In particular, oncogenic translocations between immunoglobulin loci and BCL6, BCL2, MYC and PAX5 have been reported.2 Microsatellite instability (MSI) has a critical role in the pathogenesis of hereditary non-polyposis colon cancer (HNPCC) and Muir–Torre syndrome (HNPCC with sebaceous tumours).3 ,4 However, haematological malignancies are not typical in patients with these genetic lesions. We report a patient with a Muir–Torre variant HNPCC who subsequently developed DLBCL.
An elderly patient with a history of Muir–Torre variant HNPCC presented with abdominal pain, worsening over the preceding 1–2 months, with associated weight loss of 5 kg. The past medical history included metachronous rectal, colonic adenocarcinomas, pancreatic and jejunal carcinomas, sebaceous adenomas, sebaceous epithelioma, and non-melanoma skin cancers for which they had multiple curative surgical procedures and neoadjuvant chemoradiation. There was no history of immunodeficiency. Imaging demonstrated a stricture in the distal jejunum with intensely 18F-fluorodeoxyglucose avid bowel wall thickening. At laparotomy, a 5.5 cm ulcerated mass resected. Histological evaluation showed a full thickness lymphoid infiltrate, ulcerating the overlying mucosa and penetrating serosa, forming adhesions with the adjacent loop of small intestine. The cells were intermediate to large, with vesicular chromatin and small nucleoli (figure 1A, B). The cells were positive for CD20, CD10, BCL2 and BCL6, and negative …