Rhinocerebral mucormycosis: Pathology revisited with emphasis on perineural spread.

AIMS AND OBJECTIVES: To study the histopathological features with particular emphasis on perineural invasion in invasive rhinocerebral mucormycosis.

MATERIALS AND METHODS: Tissue sections from 30 patients with invasive rhinocerebral mucormycosis were included in the study. Demographic features, predisposing conditions, and clinical features were obtained from medical records. Tissue sections were reviewed with hematoxylin and eosin (H and E), Gomori's methenamine silver (GMS), and periodic acid Schiff (PAS) stains for (i) the presence and type of inflammation (suppurative/granulomatous; sparse/absent), (ii) invasion into soft tissues, and (iii) type of spread (angio/perineural) and presence of infarction/necrosis and fungal morphology.

RESULTS: The study material included 20 males and 10 females with age ranging from 15-84 years. The clinical syndromes included rhino-orbital in 15, rhinocerebral in 6, and rhino-orbito-cerebral in 9 patients. On histopathological examination, inflammation was suppurative with predominance of neutrophils in 25 biopsies. Suppurating granuloma with neutrophils, lymphocytes, and foreign body giant cells was seen in 3 biopsies. Invasion into soft tissues, muscles, and adipose tissues was seen in 20 biopsies. Angioinvasion was noted in 25 and soft tissue invasion in 20 biopsies. Peripheral nerves were identified in 19 and perineural spread was identified in 15 biopsies. In all, biopsies with perineural invasion, angioinvasion, and soft tissue invasion were seen.

CONCLUSIONS: Perineural invasion is one of the important histological features of invasive rhinocerebral mucormycosis and it indicates advanced the extent of invasion.