Diagnosis and management of a case of retroperitoneal eosinophilic sclerosing fibroplasia in a cat

Thieme, Maureen E; Olsen, Anastasia M; Woolcock, Andrew D; Miller, Margaret A; Simons, Micha C

Impression smears taken at the time of surgery were of low cellularity, with non-degenerate neutrophils and fibroblasts seen, and were considered non-diagnostic. The formalin-fixed excisional biopsy specimen of a sublumbar mass was firm to hard with central cavitations. Histologic sections (Figure 3 ) consisted of interlacing bands of dense fibrous tissue with hypertrophied fibroblasts. Neither nuclear atypia nor mitotic figures were noted in the fibroblasts. Aggregates of eosinophils, with fewer neutrophils, macrophages, lymphocytes and plasma cells, were scattered through the sclerotic tissue. Some aggregates contained Gram-positive cocci. No other microorganisms were detected with Gram stain, Giemsa stain or Grocott's methenamine silver. Despite the numerous eosinophils, mast cells were few, individualized and well differentiated. The cavitations noted grossly were foci of necrosis with numerous neutrophils. Despite the lack of gastrointestinal tissue in the biopsy specimen, the histologic findings were typical of feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF) lesions; therefore, a diagnosis of FGESF was made.