Case Report: Primary intestinal histiocytic sarcoma in a cat

TL;DR

A cat was diagnosed with and successfully treated for a rare intestinal cancer called histiocytic sarcoma.

Contribution

This is the first reported case of primary intestinal histiocytic sarcoma in a cat.

Findings

The tumor was confirmed as histiocytic sarcoma using Iba-1, CD204, and MHC-II positivity.

Surgical removal and chemotherapy led to complete remission in the cat.

The case emphasizes the need for combined imaging and immunohistochemistry in diagnosing feline intestinal tumors.

Abstract

Histiocytic sarcoma (HS) is a rare and aggressive tumor in cats, usually presenting in a multicentric or disseminated form, with gastrointestinal involvement mainly reported as part of a metastatic disease. This report describes the first documented case of a primary intestinal HS in an 11-year-old male neutered domestic short-haired cat, presenting with acute gastrointestinal signs. Diagnostic workup included ultrasonography, cytology, histopathology, and immunohistochemistry (IHC), which confirmed a histiocytic origin through Iba-1, CD204 and MHC-II positivity and MUM1, CD117 and Desmin negativity. The patient underwent surgical excision via enterectomy, followed by adjuvant lomustine chemotherapy, achieving complete remission. Despite transient chemotherapy-induced myelosuppression, the cat remains alive and disease-free 2 years after diagnosis. This case highlights the importance of combining imaging, histopathology, and IHC when diagnosing feline intestinal masses.

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