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Cutaneous lymphoid hyperplasia mimicking cutaneous lymphoma in a hyperthyroid cat
Elisabeth Snead1, Moira Kerr, Valerie Macdonald
1Department of Small Animal Clinical Sciences (Snead, MacDonald), Prairie Diagnostic Services (Kerr), Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4.
Insights
A cat with hyperthyroidism developed severe lymphadenopathy after methimazole treatment, mimicking lymphoma. This highlights the importance of recognizing drug-induced hypersensitivity in feline medicine.
Area of Science:
- Veterinary Medicine
- Internal Medicine
- Feline Health
Background:
- Hyperthyroidism is a common endocrine disorder in older cats.
- Eosinophilic lymphadenitis is an inflammatory condition affecting lymph nodes.
Observation:
- A 12-year-old domestic shorthair cat presented with chronic lip lesions, weight loss, vomiting, and alopecia.
- The cat was diagnosed with hyperthyroidism and regional eosinophilic lymphadenitis.
Findings:
- Treatment with methimazole, an anti-thyroid drug, worsened the cat's condition.
- Generalized lymphadenopathy developed, which histologically resembled lymphoma.
- This suggested an underlying hypersensitivity disorder exacerbated by methimazole.
Implications:
- Methimazole can trigger or worsen hypersensitivity reactions in susceptible cats.
- Generalized lymphadenopathy in cats can be a sign of drug-induced hypersensitivity, not always neoplasia.
- Clinicians should consider drug reactions when evaluating cats with worsening lymphadenopathy during treatment.
Abstract:
A 12-year-old neutered male domestic shorthair cat presented for chronic, localized, swelling and crusting of the left upper lip, weight loss, sporadic vomiting, and focal alopecia between the scapulae was diagnosed with hyperthyroidism and regional eosinophilic lymphadenitis. Treatment with methimazole exacerbated an underlying hypersensitivity disorder leading to marked generalized lymphadenopathy that histologically mimicked lymphoma.
