Granulomatosis with polyangiitis (GPA) is a rare systemic disease classified as a type of systemic vasculitis, which can lead to life-threatening complications.1 Pulmonary carcinoid tumors are also uncommon entities, accounting for less than 1% of all lung cancers. They are derived from neuroendocrine cells, and are divided into 2 subcategories: typical and atypical carcinoids. The diagnostic process for these tumors can be challenging.2

A 35-year-old man, with no previous medical history except for smoking, initially presented to a community hospital with acute kidney injury. Immunological tests showed a high titer of antineutrophil cytoplasmic antibodies (ANCA; cytoplasmic ANCA titer, 1:320; proteinase 3 ANCA level, 164.8 U/ml, reference range <⁠20 U/ml). Renal ultrasound showed no features of chronic kidney disease. Computed tomography (CT) of the chest showed infiltration of the inferior lobe of the left lung. The Birmingham Vasculitis Activity Score was 5 points (3 points for acute deterioration of the kidney function, 1 point for the presence of red blood cells in the urine sediment, and 1 point for lung infiltration), which corresponded to severe disease. Based on the clinical picture of rapidly progressive glomerulonephritis, lung lesions, and the presence of ANCA antibodies, GPA was diagnosed, and the patient received high doses of methylprednisolone and 1 dose of cyclophosphamide (CP). Also, due to the still rising serum creatinine level, renal replacement therapy was initiated. Because of the unclear etiology of the lung lesions, bronchoscopy was performed, which revealed an obstructive endobronchial mass in the left lower lobe. Unexpectedly, biopsy results showed features of a typical carcinoid tumor.

The patient was then admitted to our department for further diagnosis and treatment. During the hospitalization, another pulse of CP was administered, and a permanent catheter for hemodialysis was inserted. High-resolution CT confirmed the pathologic mass corresponding to a carcinoid tumor (Figure 1A–1D), and showed regression of the inflammatory lesion in the lower lobe, as compared with the previous CT scan. Finally, a multidisciplinary team evaluated the patient and he was referred for sleeve lobectomy of the left left lower lobe with lymphadenectomy. Histopathologic examination of the lung tissue confirmed features of a typical carcinoid; fortunately, there were no metastases in the lymph nodes. The postoperative period was complicated by an upper respiratory tract infection, and the patient required a short-course intravenous antibiotic therapy (ceftriaxone).

Figure 1. A–D – high-resolution computed tomography scans showing an endobronchial mass in the left lower lobe (arrows) corresponding to a carcinoid tumor (A, D – cross-sectional view; B – longitudinal view; C – saggital view)

It was decided not to perform a kidney biopsy, because the clinical picture was suggestive of GPA, and the biopsy would not change the treatment strategy. Moreover, the biopsy would be associated with a high risk of complications due to ongoing hemodialysis procedures.

The patient continued treatment for GPA as 1-day hospitalizations at our department. Currently, induction therapy has been finished, and he remains dialysis-dependent.

The diagnosis of GPA is difficult to establish, and a coexisting carcinoid tumor makes it even more challenging. In the available literature, there has only been 1 case described of these 2 diseases occurring together.3 However, there have been 2 other case reports of a carcinoid coexisting with giant cell arteritis4,5 (Supplementary material, Table S1). Treatment of a patient suffering from these 2 entities requires cooperation of a multidisciplinary team. Carcinoid tumors may vary in terms of their histologic picture, which influences the course of the disease. Our patient was diagnosed with a typical carcinoid tumor; therefore, the treatment involved surgery. However, the immunosuppressive GPA treatment and renal replacement therapy made the surgery more prone to complications, such as infections, bleeding, and impaired wound healing.

To date, only 3 cases of coexisting vasculitides and carcinoid tumors have been reported in the available literature. The presented case shows a complex clinical picture of these diseases and their treatment in a single patient, underlining the necessity of multidisciplinary cooperation.