Case Report: Adrenal gland splenosis mimicking a neuroendocrine tumor on 68Ga-DOTATATE and 18F-FDG PET/CT imaging

Abstract

Splenosis occurring in adrenal glands is relatively rare and is easily misdiagnosed as neoplastic lesions. Herein, we present a case of a 39-year-old woman who underwent a pancreatic tail resection and splenectomy 8 years ago due to caudal pancreatic neuroendocrine tumor and splenic invasion. She underwent abdominal ultrasound examination in an external hospital a month ago due to abdominal discomfort and found a lump in the left adrenal gland. She was admitted to our hospital for further diagnosis and treatment. Abdominal computed tomography (CT) examination revealed a nodule of equal soft tissue density on her left adrenal gland, which presented obvious uniform enhancement on contra-enhanced CT. Subsequently, she underwent fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) and gallium-68 labeld 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraaceticacid -D-Phel-Tyr3-Thr8-OC (⁶⁸Ga-DOTATATE) positron emission tomography (PET)/CT imagings, and showed slightly increased ¹⁸F-FDG uptake and obviously increased ⁶⁸Ga-DOTATATE uptake in the lesion, suggesting the possibility of neuroendocrine tumor metastasis. However, postoperative pathology confirmed that the lesion was splenosis. Our case suggests that adrenal gland splenosis should be considered as a differential diagnosis of adrenal tumors, understanding the clinical and imaging features of splenosis can reduce misdiagnosis and avoid unnecessary surgical intervention.

Keywords: CT; PET/CT; adrenal gland; neuroendocrine tumor; splenosis.

Figure 1

(A) Abdominal computed tomography (CT) revealed a soft tissue density nodule about 2.8 cm × 2.0 cm in size on the left adrenal gland (arrow); In the arterial phase (B), venous phase (C), and delayed phase (D) of contrast-enhanced CT, the lesion showed obvious and continuous uniform enhancement (arrows).

Figure 2

(A–D) Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT imaging of the patient; The maximum intensity projection (MIP, A) showed a slightly increased ¹⁸F-FDG uptake in the left upper abdomen (arrow). Axial CT (B) showed an isodense nodule in the left adrenal gland (arrow). The corresponding lesion had mildly increased ¹⁸F-FDG uptake on axial PET (C, arrow) and PET/CT fusion (D, arrow), with a maximum standardized uptake value (SUVmax) of 2.7. (E–H) ⁶⁸Ga-DOTATATE PET/CT imaging; The MIP (E) showed a significantly increased ⁶⁸Ga-DOTATATE uptake in the left upper abdomen (arrow). Axial CT (F), PET (G) and PET/CT fusion (H) showed this increased focal uptake in the left adrenal gland (arrow), in the same location as the lesion shown on ¹⁸F-FDG PET/CT, with a SUVmax of 24.3.

Figure 3

Hematoxylin–eosin staining (magnification, ×100) showing red pulp (black arrow) and white pulp (red arrow) within the tissue, suggesting splenic tissue.