Intrapancreatic accessory spleen mimicking pancreatic malignancy: Diagnostic role of Tc-99m heat-damaged red blood cell scintigraphy.

Solid lesions of the pancreatic tail pose a significant diagnostic challenge due to their potential overlap with malignant neoplasms on conventional imaging. Intrapancreatic accessory spleen is a rare benign entity that may closely mimic pancreatic neuroendocrine tumors and other malignancies, leading to unnecessary invasive procedures. We present a 40-year-old male with an incidentally detected 2 cm pancreatic tail mass that demonstrated imaging characteristics similar to those of the spleen on contrast-enhanced computed tomography and magnetic resonance imaging. Following a multidisciplinary tumor board decision, Tc-99m heat-damaged red blood cell scintigraphy with single-photon emission computed tomography was performed, revealing focal radiotracer uptake in the pancreatic tail lesion with intensity and distribution identical to those of the native spleen, confirming the diagnosis of intrapancreatic accessory spleen. This case illustrates the decisive diagnostic value of Tc-99m heat-damaged red blood cell scintigraphy in differentiating intrapancreatic accessory spleen from pancreatic malignancies, thereby preventing unnecessary surgical intervention.