Case Report: Giant Multiloculated Pseudocystic Jejunal Leiomyosarcoma in a Dog: Atypical Morphologic Features of Canine Intestinal Leiomyosarcoma

Abstract

A 10-year-old intact female Rottweiler dog weighing 29 kg presented with 2 days history of vomiting, anorexia, and lethargy to KonKuk University Teaching Hospital, Seoul, South Korea. Ultrasonography and computed tomography (CT) scannings revealed a well-demarcated, large mass (29 × 19 × 11 cm) with numerous fluid-filled cavities. Metastases to adjacent lymph nodes were also identified on CT. This large mass and the affected intestinal segments were excised for palliative purposes. Postoperatively, the dog recovered uneventfully without any complications. The cut surface of the mass showed an exophytic growth pattern of multiloculated cystic lesions filled with serosanguineous fluid, large cavities filled with necrotic exudate, and fistulous connections between the intestinal lumen and the necrotic cavity in the mass. On histopathology, the mass was a spindle cell neoplasm expanding from the jejunal muscular layer and with pseudocystic changes. Additional immunohistochemical analysis using antibodies against smooth muscle actin, desmin, and CD-117 demonstrated that the mass was consistent with a leiomyosarcoma. Six months post-operatively, plain radiography revealed an abdominal mass, suspected to be recurrence from jejunal leiomyosarcoma. The owner decided to euthanize the dog due to financial constraints. This case report describes the atypical morphology and clinical progression of a large canine jejunal leiomyosarcoma, which had similar clinical features as those of human leiomyoma and leiomyosarcoma.

Keywords: dog; giant; jejunal; leiomyosarcoma; necrotic cavitation.

Figure 1

Diagnostic images at presentation. Dorsoventral (A) abdominal radiographs revealed a large soft tissue opacity located at the mid abdomen (white arrows). Post-contrast dorsal (B) and transvers (C) computed tomography scanning images of the mass (yellow dotted line, size of 29 × 19 × 11 cm). Connections between the cavity within the mass and the intestinal lumen represent the presence of fistulation (yellow arrow).

Figure 2

Macroscopic images during surgery. (A) Giant intraperitoneal mass is exposed intraoperatively with adherent jejunum. (B) The giant, multiloculated cystic mass is located at the jejunal mesentery and attached to the mesenteric border of the surrounding jejunal segment (white arrows). (C) The mass and the adhered jejunal segment are completely removed via the jejunal resection and anastomosis.

Figure 3

Gross photographs of the resected mass and jejunal segment. (A) Antimesenteric side view shows the mass with multicystic appearance. (B) The cut surface of the mass indicated as white dotted square in (A) reveals polycystic changes. (C) Oval-shaped fistula (white arrows) with surrounding mucosal ulceration is exposed through jejunal incision indicated as yellow dotted line in (A). The cut surface of the fistulated intestinal wall reveals the exophytic growth pattern of the mass and the connection between intestinal lumen and necrotic cavity located at the core of the mass. C, cavity; IL, intestinal lumen.

Figure 4

Histopathology and immunohistochemistry (IHC) of the jejunal mass. (A) The spindloid neoplastic cells are haphazardly arranged in short bundles and streams with multiple pseudocystic structures. HE stain, Bar, 500 μm. (B) The neoplasm is composed of spindle cells with indistinct cell borders, wispy eosinophilic cytoplasm and oval nucleoli. HE stain, Bar, 50 μm. (C) Neoplastic cells demonstrate negative labeling with CD117. IHC, DAB chromogen, Bar, 50 μm. (D) Neoplastic cells show strong cytoplasmic labeling with Smooth muscle actin. IHC, DAB chromogen, Bar, 50 μm. (E) Neoplastic cells show strong cytoplasmic labeling with Desmin. IHC, DAB chromogen, Bar, 50 μm.