Unresectable perineal cuniculatum carcinoma: partial remission using systemic isotretinoin and interferon-α2a therapy.

Carcinoma cuniculatum (CC) is a rare variant of verruci-form squamous cell carcinoma (SCC) without metastatic potential. Curative treatment usually requires large surgical resection. We describe here a case of perineal CC complicating giant condyloma in an HIV-infected patient treated with combined systemic isotretinoin and interfe-ron therapy when surgery, radiotherapy or chemotherapy could not be used. A 42-year-old man was referred to our department with an ab-scessed perineal mass that had been evolving for 5 years without improvement after several antibiotic treatments. The patient had been co-infected with HIV and hepatitis B virus for 17 years and had a medical history of condylomas of the anal margin. With highly active antiretroviral therapy, HIV viral load was undetectable (T-lymphocytes CD4 + count: 340/mm 3). His overall health condition was good, despite recurrent well-tolerated acute fevers. A smooth, cauliflower-like verrucous mass involved the right buttock and extended toward the anal margin, the scrotum and the opposite buttock (Fig. 1A). Multiple fistulas surrounded the mass and drained pus from which multi-resistant Pseudomonas aeruginosa was isolated. Magnetic resonance imaging (MRI) showed a subcutaneous mass of the right gluteal region infiltrating the underlying muscles, containing small collections of necrosis and several fistulas (Fig. S1A 1). Pathological re-examination of a surgical biopsy specimen obtained 2 years previously showed a neoplastic epidermal proliferation, the architecture of which consisted in deep endophytic invaginations into a fibro-inflammatory tissue (Fig. S2A 1), the invasive component presenting CC features (Fig. S2B 1). There was no area of usual-type SCC. Human papillomavirus (HPV) 6 was identified by PCR. A diagnosis of CC complicating giant condyloma/Buschke-Löwenstein tumour (BLT) was finally rendered. Owing to the large extent of tumour invasion with involvement of gluteal muscles and the proximity of the pelvic bones, curative surgery was rejected as well as radiotherapy and chemotherapy because of an expected increased risk of sepsis. Interferon (IFN)-α2a (3MUI subcutaneously once a day) and isotretinoin (1 mg/kg per day per os) were initiated, as well as adequate antibiotics and daily drainage of the collected masses. Cidofovir (5 mg/kg intravenously on weeks 0, 1, 3 and 5) was also started, but discontinued after the third administration due to moderate renal failure. Clinical and radiological reassessment after 4 weeks of therapy showed a 50% tumour collapse (Fig. 1B and Fig. S1B 1). At that time, the occurrence of a major depressive syndrome led us to interrupt interferon treatment. Isotretinoin was maintained alone at …