Overcoming Diagnostic Challenges: Abdominal Soft Tissue Sarcoma in a German Shepherd

Background: Abdominal soft tissue sarcomas (STSs) in dogs are diagnostically challenging due to their deep location, variable biological behavior, and limited accessibility for imaging. Patient-related constraints further complicate diagnostic workups. This report describes a practical diagnostic approach for an abdominal wall–associated STS when full radiographic evaluation was not feasible. Methods: A ۶-year-old intact male German Shepherd was presented with progressive abdominal distension. Physical examination revealed a firm, non-movable mass located in the caudoventral left abdominal wall, extending laterally and protruding outward from the body contour, yet not attached to any internal organ. The mass appeared to originate from or be firmly attached to the abdominal musculature/fascia, consistent with a superficial soft tissue tumor. The dog exhibited marked intolerance to restraint, allowing acquisition of only a single ventrodorsal radiographic projection. Radiography was performed using a CR system (Agfa CR) with exposure settings of kVp ۵۷ and mAs ۳.۲. The view demonstrated a well-defined soft-tissue mass with no visible evidence of abdominal metastasis. Thoracic radiographs were unremarkable. Abdominal ultrasonography was performed using a Sonoscape E۲ system with a high-frequency linear probe appropriate for superficial soft tissue evaluation. The imaging depth was adjusted to low due to the superficial location of the mass. Ultrasound revealed a well-encapsulated, mildly heterogeneous soft-tissue mass measuring ۲۴ mm, with mild central vascularization on color Doppler. No free abdominal fluid or additional lesions were identified. Ultrasound-guided fine-needle aspiration (FNA) was performed. Cytologic evaluation yielded a highly cellular sample dominated by spindle-shaped mesenchymal cells with marked anisokaryosis, anisocytosis, nuclear pleomorphism, and high N:C ratio. Occasional multinucleated cells and sparse mitotic figures were noted. The findings were consistent with a low-to-moderate grade mesenchymal sarcoma. Results: The imaging and cytological findings together supported the diagnosis of an abdominal wall soft tissue sarcoma with features consistent with a low to moderate grade malignancy. Despite limited radiographic projections, ultrasonography combined with cytology provided sufficient diagnostic clarity regarding the mass origin, biological behavior, and staging.