Mycobacterial Spindle Cell Pseudotumor Presenting as a Pancreatic Head Mass: A Case Report.

Mycobacterial spindle cell pseudotumors (MSCPs) are rare lesions characterized by the proliferation of spindle-shaped histiocytes caused by mycobacterial infections. MSCPs have been reported in the lung, lymphatic system, and skin of immunodeficient patients. We present the case of a spindle cell pseudotumor of the pancreas in a 30-year-old male with advanced human immunodeficiency virus (HIV) infection, which led to biliary stricture, splenomegaly, chronic pancreatitis, portal hypertension, compression of the hepatic artery and portal vein, and ascites. This was the patient's third mycobacterial infection diagnosis. The MSCP was diagnosed via endoscopic biopsy after two prior non-diagnostic biopsies of the pancreatic lesion. Following 18 months of tailored antimycobacterial therapy, the pancreatic mass resolved radiographically with normalization of liver tests and sustained clinical improvement, and there has been no relapse more than 8 months after treatment completion. This case highlights the presentation of an MSCP in a unique anatomic location not previously documented and the challenges encountered with diagnosis and management.