A Rare Case of Intra-Oral Dirofilariasis Manifesting on The Buccal Mucosa

Abstract

Dirofilariasis is a rare zoonotic disease endemic in tropical and sub-tropic countries, including India. Caused by the nematode of the genus Dirofilaria, the disease usually affects canines which form the primary hosts. Humans rarely get infected through the bite of potential mosquito vectors. Manifestations in humans have been reported to affect the orbital region, and intra-oral involvement is rarely reported. Our case was a 5-year-old boy who presented with a slow-growing diffuse swelling on the buccal mucosa. Dirofilariasis was diagnosed when the excised specimen was subject for histopathologic evaluation, yielding the identification of the Dirofilaria worm with the typical morphologic characteristics in the tissue sections. An extremely rare occurrence intra-orally, dirofilariasis can manifest as subcutaneous nodules. Pathologists have an important role in the final diagnosis of the disease through identifying the adult worm in the tissue sections of the biopsy specimen. Dental practitioners must be aware of such an entity as rarely this can be encountered in routine dental practice.

Keywords: Dirofilaria repens; Dirofilariasis; Oral; Sub-cutaneous nodule.

Fig. 1

Extra-oral clinical photograph. A) Slight facial asymmetry visible on the right side of the face in the cheek region, B) A diffuse swelling on the right side of the face above the lower border of the mandible in the cheek region

Fig. 2

Photograph of the gross specimen. The excised specimen appeared as a brownish white cystic sac with a smooth outer surface

Fig. 3

Histologic examination of the excised lesion. A) An intense granulomatous inflammatory response surrounding the parasite (H&E stain, 4X), B) a Cross-section of the adult worm surrounded by a dense inflammatory response (H&E stain, 10X)

Fig. 4

Histologic examination of the excised lesion. A) Cross-sectional morphology of the Dirofilaria worm where the outer cuticle (C) shows longitudinal ridges (R) and an inner pseudocoel cavity (P) (H&E stain, 40X). B) Cross-sectional morphology of the Dirofilaria worm showing a well-developed inner musculature (M) attached to the outer cuticle (C) and lining the peudocoel cavity (P). The intestinal tubule (IT) and the genital tubule (GT) containing spermatocytes are also observed. (H&E stain, 40X)

Fig. 5

Histologic examination of the excised lesion. Inflammatory cells such as lymphocytes, plasma cells, macrophages, and a few eosinophils were noticed in the inflammatory response surrounding the parasite in the tissue. (H&E stain, 40X)