A Previously Undescribed Cutaneous Paraneoplastic Syndrome in a Cat with Thymoma

The study described a novel cutaneous paraneoplastic syndrome (PNS) in a 14-year-old neutered female domestic short hair cat with thymoma, presenting as noninflammatory alopecia with a dorsal multifocal distribution. Diagnostic imaging revealed a mediastinal mass, which was surgically removed and confirmed as a thymoma with multiloculated cyst formation and multifocal cholesterol granulomas. Histopathological assessment of the alopecic areas showed follicular and epidermal atrophy, trichilemmal keratinization, and mild orthokeratotic hyperkeratosis. Post-surgery, hair regrowth was observed in the previously alopecic areas. The cat was euthanized 3.5 months later due to recurrent chylothorax, suspected to be a postoperative complication. The study concluded that thymoma-associated PNS might not always manifest as exfoliative dermatitis and should be considered in the differential diagnosis of multifocal noninflammatory alopecia.