Atypical Endobronchial Carcinoid with Postobstructive Pneumonia Obscuring the Diagnosis of Granulomatosis with Polyangiitis

Abstract

Granulomatosis with polyangiitis (GPA), previously termed Wegener's Granulomatosis, is an autoimmune small vessel vasculitis which is highly associated with antineutrophil cytoplasmic antibodies (ANCA) and has varied clinical manifestations. Diagnosis hinges on identifying a combination of clinical features of systemic vasculitis, positive ANCA serology, and histological evidence of necrotizing vasculitis, necrotizing glomerulonephritis, or granulomatous inflammation from a relevant organ biopsy. The American College of Rheumatology has also developed a classification criteria focusing specifically on nasal or oral inflammation, abnormal chest radiograph, and abnormal urinary sediment, along with granulomatous inflammation, which helps to distinguish GPA from other forms of systemic vasculitis. In the case presented below, the diagnosis of GPA was delayed as the patient had a concomitant atypical endobronchial carcinoid which predisposed to postobstructive pneumonia. Fortunately, the papular lesions that developed across her lower limbs prompted further investigations. The return of appropriate serology coincided with progression to alveolar hemorrhage, offering a more complete clinical picture, and when she responded to the combination of steroid, cyclophosphamide, and plasma exchange, the diagnosis of GPA was cinched.

Figure 1

Skin biopsy showing classic features of small vessel vasculitis with neutrophilic infiltration of the vessel walls, karyorrhexis, and fibrinoid necrosis of vessel walls as well as extensive extravasation of red blood cells.

Figure 2

(a) CXR from admission showing bilateral extensive pulmonary infiltrates, suggestive of florid vasculitis. (b) CXR upon discharge emphasizing resolution of the pulmonary infiltrates following treatment with plasmapheresis, induction cyclophosphamide, and high dose methylprednisone.

Figure 3

Bronchoscopy image showing the gross carcinoid tumor in the left mainstem bronchus.

Figure 4

CTA chest showing bilateral ground glass opacities and highlighting the left endobronchial lesion (yellow circle).

Figure 5

Cell block section of bronchoalveolar lavage showing hemosiderin-laden macrophages (granular golden pigment) demonstrating alveolar hemorrhage.

Figure 6

Histology slide from the atypical carcinoid tumor. Nests of uniform, bland carcinoid cells with central nuclei and moderate cytoplasm, prominent vasculature surrounding the nests (H&E, ×20). Inset: infrequent mitoses (H&E, ×63).