Malignant transformation of an ovarian mature cystic teratoma presenting as a rectal mass

Background. Squamous cell carcinoma arising from malignant degeneration of a mature cystic teratoma is rare with a reported incidence of approximately 1-3%. The most common presenting symptoms are lower abdominal pain and inc reasing abdominal girth of several months' duration. Approximately 50% of t he patients present with FIGO stage I while 35-38% present with stage III d iseases. Case. The case described herein represents an unusual presentation and init ial diagnostic dilemma of locally aggressive squamous cell carcinoma arisin g in an ovarian dermoid cyst, with invasion into the distal rectum and anal canal causing rectal bleeding similar to the presentation of anal squamous cell carcinoma. Despite aggressive surgical management with posterior exen teration and optimal tumor debulking followed by 5040-cGy pelvic radiation utilizing 25-MV photons, the patient developed pelvic recurrence at the vag inal cuff 6 weeks after completion of her adjuvant radiotherapy. She subseq uently failed cis-platinum single-agent chemotherapy and died 9 months afte r her initial surgery and diagnosis. Conclusion. Squamous cell carcinoma in the anal canal, diagnosed by colonos copy or proctoscopy, could be an unusual presentation of that arising from malignant degeneration of an ovarian dermoid cyst. This tumor may behave in a locally aggressive manner and be resistant to pelvic radiation or single -agent chemotherapy of cis-platinum. The current experience of adjuvant tre atment after comprehensive staging and cytoreductive surgery reported in th e world literature is limited, and the optimal management of the malignancy remains unclear. (C) 1999 Academic Press.