[Extranodal NK-T-cell lymphoma, nasal type in granulomatosis with polyangiitis. A case report].

BACKGROUND: Granulomatosis with polyangiitis (GP) is a systemic necrotizing vasculitis with multi-organ involvement that primarily affects the respiratory tract and the kidneys. Fever in these patients is an indicator of activity; however, if it arises in isolation, the physician should exclude other causes. CLINICAL CASE: Male patient admitted due to an unexplained fever and weight loss; it was diagnosed GP by a history of pauci-immune glomerulonephritis, fixed pulmonary nodules and chronic sinusitis of four years of evolution; however, the fever persisted despite treatment and in the absence of infection. It was performed an oropharynx lesion biopsy and the diagnosis was extranodal NK-T-cell lymphoma, nasal type, and positive for CD56 and granzyme. CONCLUSION: Extranodal NK-T-cell lymphoma, nasal type is a rare entity, of poor prognosis, that should be considered as a diagnosis in patients with GP unresponsive to steroid. That is the reason why biopsy of the lesion and immunohistochemistry are required.