Inflammatory Myofibroblastic Tumor: Findings on ⁶⁸Ga-DOTA-NOC Positron-emission Tomography-Computed Tomography

Abstract

Inflammatory myofibroblastic tumor (IMT) or inflammatory pseudotumors are a rare group of tumors usually affecting children and young adults. They occur in various anatomic locations, with most common being the lung accounting for almost 95% of the cases. We present a case of a 4-year-old girl who presented with fever and dull abdominal pain for 6 months with a clinically palpable left hypochondrium mass. On suspicion of mesenteric/gastric neuroendocrine tumor, ⁶⁸Ga-DOTA-NOC positron-emission tomography-computed tomography was done; however, the biopsy revealed IMT.

A 4-year-old female presented with dull aching abdominal pain and fever for 6 months to the surgical outpatient department. Per abdominal examination revealed a palpable left hypochondrium mass. Contrast-enhanced computed tomography abdomen was done which revealed lobulated and peripherally enhancing mass measuring approximately 6.6 cm × 6.3 cm × 5 cm in the stomach bed region, likely arising from the greater curvature of the stomach or from the mesentery. On suspicion of neuroendocrine tumor by the concerned clinician, the patient was referred for ⁶⁸Ga-DOTANOC positron-emission tomography-computed tomography (PET-CT) to look for any additional sites of metastases. ⁶⁸Ga-DOTA-NOC PET-CT maximum intensity projection image shows increased radiotracer uptake in the abdomen region on the left side [Figure 1a, solid black arrow] which corresponds to a lobulated mass in the gastric bed region with areas of internal necrosis and calcification on axial and coronal CT images [Figure 1b and e, solid white arrows] showing increased DOTA-NOC uptake in the PET only [Figure 1c and f] and fused PET-CT images [Figure 1d and g]. Ultrasound-guided biopsy from the left hypochondrium mass showed spindle cell tumor with tumor cells arranged in fascicles, which were infiltrating at places and were embedded in a collagenous background. Immunohistochemistry showed cytoplasmic positivity for smooth muscle actin, desmin, and anaplastic lymphoma kinase-1 and negative for CD117, DOG-1, and myogenin. The overall feature was suggestive of inflammatory myofibroblastic tumor (IMT). The patient underwent surgery after the PET-CT scan as no distant metastasis was present, and the histopathology of the surgical specimen was suggestive of IMT. IMT is an uncommon mesenchymal tumor with an intermediate malignant neoplasm and usually presents in the children and young adults.[1] It can frequently recur and metastasize.[2,3] Heterogeneity in FDG uptake has been demonstrated in few of the earlier case reports likely due to variability in the population of inflammatory cells in tumor.[4,5,6,7,8] Evidence of somatostatin receptor expression has been seldom demonstrated in IMTs and through this the authors want to undermine the fact that IMTs should also be included as a potential differential diagnosis in case of mesenteric mass on ⁶⁸Ga-DOTA-NOC PET-CT apart from neuroendocrine tumors.

Figure 1.

(a) Maximum intensity projection image of ⁶⁸Ga-DOTA-NOC positron-emission tomography-computed tomography showing increased radiotracer uptake in the left lower abdominal region. (b and e) axial and coronal computed tomography images, respectively, showing a lobulated mass in the left hypochondrium with areas of internal necrosis. (c and f) axial and coronal positron-emission tomography only images, respectively, showing increased radiotracer uptake in the mass lesion. (d and g) axial and coronal fused positron-emission tomography-computed tomography image showing increased radiotracer uptake seen in the left hypochondrium mass lesion

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Conflicts of interest

There are no conflicts of interest.