[A case of pulmonary dirofilariasis]

Area of Science:

• Medical Parasitology
• Thoracic Surgery
• Diagnostic Pathology

Background:

• Pulmonary nodules detected via chest X-ray and CT scans often raise concerns for malignancy.
• Dirofilariasis, a parasitic infection typically affecting canines, can rarely manifest in humans, presenting diagnostic challenges.

Observation:

• A 76-year-old woman presented with a 2 cm round, well-defined pulmonary nodule on the right S6 segment, initially suspected as a malignant tumor.
• Video-assisted thoracoscopic surgery (VATS) was performed for partial resection.
• Initial frozen specimen examination ruled out malignancy, but formalin-fixed tissue revealed dirofilariasis.

Findings:

• Histological examination of the resected pulmonary nodule confirmed dirofilariasis, a rare parasitic lung infection.
• While imaging and serological tests can suggest dirofilariasis, definitive diagnosis relies on histopathological analysis of resected tissue.
• This case adds to the reported 97 cases of human dirofilariasis in Japan.

Implications:

• The presentation of dirofilariasis as a solitary pulmonary nodule underscores the importance of considering parasitic etiologies in differential diagnoses.
• Surgical resection is often necessary due to the difficulty in definitively excluding malignancy based on non-invasive methods.
• Accurate diagnosis through histopathology is crucial for appropriate patient management and understanding the epidemiology of human dirofilariasis.