A Case of Pentastomiasis at the Left Maxilla Bone in a Patient with Thyroid Cancer

Abstract

Pentastomiasis, a zoonotic parasite infection, is typically found in the respiratory tract and viscera of the host, including humans. Here, we report for the first time an extremely rare case of intraosseous pentastomiasis in the human maxilla suffering from medication related osteonecrosis of the jaw (MRONJ). A 55-year-old male had continuously visited the hospital for MRONJ which had primarily developed after bisphosphonate and anti-neoplastic administration for previous bone metastasis of medullary thyroid cancer. Pain, bone exposure, and pus discharge in the right mandible and left maxilla were seen. Osteolysis with maxillary cortical bone perforation at the left buccal vestibule, palate, nasal cavity, and maxillary sinus was observed by radiologic images. A biopsy was done at the left maxilla and through pathological evaluation, a parasite with features of pentastome was revealed within the necrotic bone tissue. Further history taking and laboratory evaluation was done. The parasite was suspected to be infected through maxillary open wounds caused by MRONJ. Awareness of intraosseous pentastomiasis should be emphasized not to be missed behind the MRONJ. Proper evaluation and interpretation for past medical history may lead to correct differential diagnosis and therapeutic intervention for parasite infections.

Keywords: Pentastomida; bisphosphonate-associated osteonecrosis of the jaw (BRONJ); osteonecrosis; parasite.

Fig. 1

Radiography of the patient. (A) CT view after primary maxillary bone exposure: osteolytic lesion with sequestra suspected calcification in the left maxilla perforating the cortical bone of the buccal vestibule (v), palate (p), nasal cavity (n), and maxillary sinus (m). (B) Panoramic view of the recurrent maxillary bone exposure with ill-defined radiolucent lesion (arrows) and alveolar bone loss in the left maxilla.

Fig. 2

Pathological findings of the incisional biopsy (scale bar=60 μm). (A) Histopathological view showing the caudal end of a pentastome with several false annuli (pseudosegmentation; arrows) along the body surrounded by necrotic bone fragments (HE stain, ×400). (B) Schematic drawing of Fig. 2A. (C) Serial section of Fig. 2A revealing a hook or claw-like structure (asterisks) at the cephalic end (HE stain, ×400). (D) Schematic drawing of Fig. 2C. Inset of Fig. 2D shows a more definite image of the hook/claw-like structure of the pentastome.