Heavily calcified gastrointestinal stromal tumors: Pathophysiology and implications of a rare clinicopathologic entity

Abstract

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract, and are characterized by a broad spectrum of clinical, histological and molecular features at presentation. Although focal and scattered calcifications are not uncommon within the primary tumor mass, heavy calcification within a GIST is rarely described in the literature and the clinical-biological meaning of this feature remains unclear. Cases with such an atypical presentation are challenging and may be associated with diagnostic pitfalls. Herein, we report a gastric GIST with the unusual presentation of prominent calcifications that was identified incidentally on imaging during a post-trauma diagnostic work-up. The patient underwent laparoscopic surgery with a radical resection of the mass, which was subsequently characterized by histological analysis as spindle-shaped tumor cells, positive for CD117/c-KIT, CD34 and DOG1, and with calcified areas. Given the intermediate risk of recurrence, no adjuvant therapy was recommended and the patient underwent regular follow-up for 22 mo, with no evidence of relapse. Our case can be considered of interest because of the rarity of clinical presentation and the uniquely large size of the GIST at diagnosis (longest diameter exceeding 9 cm). In closing, we discuss the pathophysiology and clinical implications of calcifications in GISTs by reviewing the most up-to-date relevant literature.

Keywords: Atypical presentation; Calcification; Computed tomography; Gastrointestinal stromal tumor; Stomach.

Figure 1

Axial contrast-enhanced computed tomography scan showing a well-defined heterogeneously enhanced gastric mass with coarse and diffuse calcifications.

Figure 2

Macroscopic presentation of the resected mass, consisting of an exophytic and yellowish-gray tumor.

Figure 3

Histologic appearance of the tumor. A and B: Interlacing bundles of spindle cells with unremarkable mitotic activity (H and E stain; magnification × 10); C and D: Calcified areas (H and E stain; magnification × 20); E: Intense immunoreactivity for DOG1 (Immunohistochemistry stain; magnification × 20); F: Inconspicuous Ki67-MIB1 label index (count rate < 1%; immunohistochemistry stain; magnification × 20).