Diagnosis of foregut and tailgut cysts by endosonographically guided fine-needle aspiration.

Foregut, hindgut, and tailgut cysts are uncommon developmental anomalies. Clinical and radiological diagnosis can present many challenges, especially in adult patients or when the lesions are in unique locations. Thus, diagnosis has traditionally been provided upon surgical resection. We describe the diagnoses of a gastric foregut cyst and a retrorectal tailgut cyst by endosonographically guided fine-needle aspiration in two adults. The common cytologic features of the specimens are ciliated epithelial cells, proteinaceous material with degenerated debris, histiocytes, and benign appearing epithelium of squamous and/or gastrointestinal type that lack cytologic atypia. The identification of ciliated columnar cells is the key finding. Cytologic diagnosis via endosonographically guided fine-needle aspiration of foregut/hindgut cyst is accurate and less traumatic than surgical biopsies.