Therapeutic Attitude in the Malignification of Pilonidal Cyst: Radical Treatment Associating Intraoperative Radiotherapy

Malignant degeneration on pilonidal cyst is an infrequent entity: less than 70 cases have been described in the literature. Predominantly in males around 50-60. Very slow evolution until its malignancy. Predilection for the sacrococcygeal area and epidermoid histology. Infrequent distant dissemination despite the important local extension of the primary tumor. Similar morphological and histological characteristics to anal carcinomas, using schemes of treatment based on radiotherapy and chemotherapy with radical intention according to locoregional and distance extension, associating subsequent surgery depending on the response. We describe a case of this pathology and its therapeutic management based on the literature review available. We present the case of a 70-year-old man with a pilonidal cyst malignancy in the sacrococcygeal region. Locally advanced and unresectable disease at diagnosis with skin, muscle, lymphatic and bone involvement. Pathological confirmation diagnosis established after thick needle biopsy, with a well-differentiated squamous cell carcinoma. It was decided to administer chemotherapy and radiotherapy treatment and, depending on the response evaluated by nuclear magnetic resonance, excision and/or intraoperative radiotherapy in the area of microscopic risk disease. In a second time, reconstruction using glute flaps. Early diagnosis and treatment are essential to improve the unfortunate prognosis. Surgery with curative intention is the standard of care according to locoregional extension in association with radiotherapy and chemotherapy if adverse factors or unresectable disease. In order to enhance local control, dose has been scaled allowing, besides, to minimize the acute toxicity derived from the treatment.