The mass is composed of nests, cords, and sheets of cells lined by delicate fibrous septa. The cells are round, regular with small uniform nuclei and infrequent mitoses. It is located in the bronchus. It is a carcinoid tumor. The patient bled profusely when the lesion was biopsied.
Carcinoid tumors are extremely vascular and thus often bleed when biopsied.
The parenchyma behind the tumor shows abundant neutrophils and thus she has a superimposed pneumonia explaining the symptoms and chest x-ray. By electron microscopy these tumors show electron dense neurosecretory granules. They often arise also in the GI tract, with the appendix being a fairly frequent site. The prognosis is usually excellent, though they may metastasize to regional nodes. The most malignant end of the neuroendocrine spectrum is oat cell, or small cell carcinoma of the lung, which has an almost uniformly fatal outcome.