Fibroliposarcoma and malignant melanoma

• Name: Boujee
• Report and medical history: canine, mixed breed; male, entire, 8 years old.

The patient was brought in due to recent loss of appetite and reduced activity for about 5 days. Occasional dysuria was also reported.

Exploratory laparotomy was performed after three days of hospitalization and medical management. At surgery, a uterus-like smooth muscle structure was identified at the location described on ultrasound findings. The body of this structure terminates in the prostate while both horns were found to extend towards their respective inguinal canals. The paraprostatic cyst was intimately associated with the right lateral wall of the urinary bladder from which it was partially separated by careful dissection. Cyst drainage and omentalization was performed. Sections of the resected cyst wall were submitted for histopathological analysis.

The patient was discharged after three days of hospitalization and the clinical signs resolved.

The tissue sections present streams of large plump fibroblasts showing moderate anisocytosis and anisokaryosis with large pleomorphic nuclei and distinct nucleoli interspersed with varying clusters of poorly differentiated adipocytes, some with scant to abundant cytoplasmic fats deposits. The neoplastic adipocytes show mild to moderate anisocytosis and anisokaryosis with large pleomorphic nuclei and prominent nucleoli. Large areas of necrosis with moderate to marked neutrophilic infiltration. Sparsely distributed large melanocytes with abundant intracytoplasmic melanin granules seen in some areas of the tissue section and intravascular infiltration. The neoplastic melanocytes show moderate anisocytosis and anisokaryosis with pleomorphic nuclei mostly obscured by melanin granules.

Vascularization is moderate; mitotic activity is moderate (10-12/10 hpf).

Mixed Tumor (Fibroliposarcoma and Malignant Melanoma).

The changes observed in the prostate gland, localized steatitis, pain during probe manipulation and possible reactive medial iliac lymph node are highly suggestive of prostatitis with concurrent benign prostatic hyperplasia. The large intraabdominal solitary cyst with direct communication to the prostate is characteristic of a paraprostatic cyst. The cystitis should be considered with mucosal irregularity of the apical urinary bladder. For further investigation, ultrasound-guided needle aspiration was performed for urine and paraprostatic fluid analysis. One of the conditions associated with paraprostatic cyst is uterus musculinis. The observed tubular structure bounded dorsally by the colon and ventrally by the urinary bladder is possibly a derivative of the Müllerian duct. The heterogeneity of the medial iliac lymph nodes can be due to reactivity to underlying prostatic abnormality, paraprostatic cyst or due to developing neoplastic changes. The findings on the gallbladder is suggestive of biliary sludge or a developing gallbladder mucocele.