A Rare Case of Malignant Granular Cell Tumor of the Colon Incidentally Detected by (18) F-FDG Positron Emission Tomography/Computed Tomography.

Abstract

We report an unusual case of malignant granular cell tumor (GCT) of the colon incidentally detected by Fluorine-18-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in a 54-year-old female patient with history of pulmonary adenocarcinoma. 18F-FDG-PET/CT showed an area of increased radiopharmaceutical uptake, corresponding to a 3 cm nodule in the caecum. Based on PET/CT findings, the patient underwent endoscopic resection of the colonic lesion. Histology demonstrated the presence of a malignant GCT of the colon (Figs. 1 and ​and22). Fig. 1 A 54-year-old female with previous history of pulmonary adenocarcinoma surgically treated underwent 18F-FDG-PET/CT for restaging due to the increased tumor markers levels. Fig. 2 Based on the PET/CT findings, the patient underwent colonoscopy and endoscopic resection of the colonic lesion. Low-power microphotograph (A; hematoxylin and eosin: magnification x20) showed the lesion in the wall of the large bowel covered by colonic ... GCT is a rare tumor of neural origin that occurs in the fourth to sixth decade of life. Although most of these tumors are benign, 1–3 % of all GCTs are malignant [2, 3]. GCTs usually present as solitary painless nodules in the dermis or subcutaneous tissues. They can also be found in internal organs including the larynx, bronchus and gastrointestinal tract [2]. Colonic GCT is mostly found incidentally during colonoscopy or surgical resection as a solitary submucosal sessile nodule, although, some lesions may cause rectal bleeding [2]. The role of 18 F-FDG-PET and PET/CT in patients with GCTs localized in various anatomic sites was reported by few articles in the literature [4–8]. A case of benign GCT of the colon detected by 18 F-FDG-PET/CT has been recently described by Oh et al., and maximum standardized uptake value was 9.1 [8]. To the best of our knowledge, this is the first case of a malignant GCT of the colon incidentally detected by 18 F-FDG-PET/CT described in the literature. In particular, as in our case, 18 F-FDG-PET/CT may allow the correct identification and metabolic assessment of a rare malignant and asymptomatic tumor that presented as focal area of increased 18 F-FDG uptake in the colon [9].