Solid type primary intraosseous squamous cell carcinoma in a long hair cat

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare and aggressive malignancy that originates within the bone, reported in both humans and animals. While squamous cell carcinoma is the most common oral tumor in cats, PIOSCC is an uncommon variant with distinct clinical and pathological features.

A 10-year-old spayed female domestic longhair cat presented with a progressively enlarging mass at the rostral mandible. Over 6 weeks, the cat exhibited clinical signs including inappetence, excessive salivation, and pain. Diagnostic evaluations comprised hematology, serum biochemistry, head radiographs, fine needle aspiration, and histopathology. A diagnosis of solid-type PIOSCC was confirmed post-mortem, based on histopathological and immunohistochemical findings.

This case represents the first documented instance of solid-type PIOSCC in a cat in Jordan. It highlights the importance of early recognition and accurate diagnosis of this rare, locally invasive tumor. Given the poor prognosis, humane euthanasia was chosen as the most appropriate course of action.