Squamous cell carcinoma in a retrorectal cystic hamartoma

Retrorectal cystic hamartomas (HCR) (“tailgut cyst” in English-language literature) are congenital cystic tumors derived from vestiges of the hindgut. Its incidence is low, being more frequent in adult women. They are variable in size, uni or multiloculated. They can be lined with several types of epithelia (squamous, transitional, mucinous,...) in a same cyst and can contain mucus. Lesions usually present during adulthood due to pain, discomfort, rectal bleeding, infection, or malignant transformation. The incidence of malignancy is low, being adenocarcinoma and neuroendocrine the most frequent tumors associated to HCR. We present a case of HCR associated with squamous cell carcinoma and discuss aspects of the treatment.