ALK+ Anaplastic Large Cell Lymphoma With Bladder Involvement Presenting as Fever of Unknown Origin: A Case Report and Literature Review.

Anaplastic large cell lymphoma (ALCL) is a rare malignant tumor normally originating in lymph nodes, though it can occur in extranodal sites. We report a 59-year-old man with anaplastic lymphoma kinase (ALK) positive ALCL involving the bladder diagnosed post-mortem who presented with fever of unknown origin. This is the seventh reported case of ALCL presenting as a bladder neoplasm. The patient presented to his primary care physician with a several day history of fever. An eventual computed tomography scan of the abdomen and pelvis showed widespread adenopathy in the pelvis and retroperitoneum. After a negative infectious investigation, the patient underwent exploratory laparotomy with excisional biopsy of periaortic lymph nodes. Pathology revealed reactive lymphocytes. Bone marrow biopsy also was negative for malignancy. The patient's fevers persisted, and he later exhibited dysuria and hematuria with evidence of bilateral hydronephrosis. Cystoscopy revealed an erythematous, diffusely friable bladder mucosa with inaccessible ureteral orifices, and biopsies were taken. The patient continued to deteriorate clinically because of associated macrophage activation syndrome, a close variant of hemophagocytic lymphohistiocytosis, and expired the following day. Autopsy was declined. Post-mortem pathology reports from cystoscopy revealed ALK+ ALCL of the bladder.