Retrorectal cystic hamartoma - Report of 5 cases with malignancy arising in 2

Background.-Retrorectal cystic hamartomas, or tailgut cysts, are rare conge nital lesions that typically present as presacral masses. These lesions are frequently clinically unrecognized and misdiagnosed. Malignant change is e xtremely rare. Only 10 additional cases with associated malignancy were rec overed from the literature. We describe the clinicopathologic features of 5 cases, including 2 cases with malignant transformation. Results.-All patients were women (age range, 36-69 years). The most common symptoms were pain with defecation and rectal bleeding. One patient was asy mptomatic. All lesions presented as multicystic presacral masses and all we re surgically resected. The lesions varied in size from appoximately 2 to 1 2 cm (average, 9.5 cm) and overall had similar histology composed of a vari ety of epithelial linings (stratified squamous, transitional, and simple or ciliated pseudostratified columnar). Skin adnexa, neural elements, and het erologous mesenchymal tissue, discriminators between retrorectal cystic ham artoma and teratoma, were not identified. Arising in association with the c ysts was a focus of adenocarcinoma in one case and a neuroendocrine carcino ma in another. Conclusions.-The clinical diagnoses in our cases were often delayed, which in part may be due to unfamiliarity with this entity. The main diagnostic d ifficulty is distinction from presacral mature cystic teratomas and rectal duplication cysts. Tailgut cysts require complete surgical excisions to pre vent future recurrences and to preclude possible malignant transformation. Meticulous gross examination and adequate sampling are important to documen t the exact nature of these cysts and to rule out possible coexisting malig nancies, which may he focal.