Dermatitis by malassezia spp. In a dog with negative cytology: importance of clinical-therapeutic correlation – Case report

Abstract

Introduction: Canine malasseziosis is a common opportunistic dermatopathy caused by the overgrowth of Malassezia pachydermatis, a commensal yeast of canine skin. Diagnosis is based on the association between clinical findings and complementary diagnostic tests, particularly cutaneous cytology, although false-negative results may occur and hinder diagnostic confirmation.Objective: To report a clinical case of Malassezia spp. dermatitis in which the diagnosis was established through clinicotherapeutic correlation following a false-negative cutaneous cytology result.Case report: A 7-year-and-11-month-old female Pinscher dog was presented with intense pruritus, characteristic rancid odor, lichenification, hyperpigmentation, and skin thickening affecting the axillary and thoracic regions. Despite the absence of yeast on cytological examination, the clinical findings were highly suggestive of malasseziosis. Discussion: Factors related to collection technique, irregular distribution on the skin surface, or fungal load can compromise the sensitivity of cytology. Aligned with the guidelines of the World Association for Veterinary Dermatology (WAVD), the diagnosis of malasseziosis requires an integrated approach that correlates history and physical examination, avoiding reliance on or isolated interpretation of a single laboratory method.Conclusion: This case demonstrates that false-negative cytological results do not exclude the diagnosis of Malassezia spp. dermatitis when compatible clinical findings are present. The integration of clinical history, physical examination, and therapeutic response proved essential for clinical decision-making and diagnostic establishment.