肺転移を伴う耳下腺癌との鑑別を要した多発血管炎性肉芽腫症例

抄録

Granulomatosis with polyangiitis (GPA) is characterized by systemic vasculitis with necrotizing granulomatous inflammation and pauci-immune small-vessel vasculitis. The initial symptoms are usually nasal or paranasal sinus lesions, and GPA with parotid swelling is rare. We report the case of a patient who presented with a parotid swelling, who was finally diagnosed as having GPA.

A 72-year-old man presented with a large mass measuring 30 mm in diameter in the left parotid gland with indistinct borders and contrast enhancement. Fine-needle aspiration (FNA) cytology revealed no evidence of malignancy. Chest CT showed multiple nodular shadows with spicula in the lower lung lobes bilaterally, suggestive of pulmonary metastases from parotid carcinoma. Transbronchial biopsy showed an inflammatory cell infiltrate consisting mainly of lymphocytes and histiocytes, with necrosis. Therefore, we suspected vasculitis and performed serology for ANCA, which revealed a PR3-ANCA titer of 74.3 U/mL. After a second otorhinolaryngological screening, left otitis media with effusion was diagnosed. We made the diagnosis of GPA and started the patient on remission induction therapy. After the treatment, the test for PR3-ANCA became negative and the parotid and pulmonary lesions showed marked resolution.

GPA with parotid involvement is rare, and delays in diagnosis are common. Early diagnosis and treatment are important because early treatment is associated with a high likehood of remission. Therefore, we considered it advisable to screen the otorhinolaryngological and pulmonary areas and perform additional close examination in patients presenting with a parotid swelling, considering the possibility of GPA.