Pulmonary cryptococcoma in a Friesian horse in the Netherlands

A 6-year-old female Friesian horse was admitted with pyrexia, dullness, weight loss, watery faeces and mild bilateral mucoid nasal discharge. Radiographic and ultrasonographic examination of the thorax indicated a large mid-thoracic soft tissue mass, and the horse was euthanased because of a poor prognosis. At postmortem examination, it was found that the lung tissue was partly replaced by multiple to coalescing soft tissue lesions with a yellow gelatinous aspect, varying in size up to 15 × 15 × 20 cm. Histologically, the mass showed mild pyogranulomatous inflammation associated with large numbers of globular encapsulated 10–20 μm yeasts with or without narrow-based budding, consistent with multiple coalescing cryptococcomas. Quantitative PCR testing of formalin-fixed paraffin-embedded tissue led to the identification of Cryptococcus gattii species complex. To the authors’ knowledge, this is the first case reported in the Netherlands of pulmonary cryptococcomas due to C. gattii sensu lato in a horse that had never travelled abroad.