Capillary network contributing to the cytological diagnosis of bronchial carcinoid

We encountered a case of bronchial carcinoid in which the brushing cytology diagnosis was assisted by the presence of a capillary network. An atelectatic X-ray shadow in the left lung field of a 52-year-old man was identified as a nodule obliterating the B8 bronchus. Brushing cytology of the nodule revealed numerous tufts of a capillary network along with small round cells with mild nuclear atypia. Although biopsy was non-contributory, an assumption of carcinoid was made. The diseased lobe with the nodule was resected and typical carcinoid was diagnosed histologically. In cytological diagnosis, supporting components of the disease morphology may also provide important clues to the diagnosis.