Sebaceous carcinoma

Sebaceous carcinoma, also known as sebaceous gland carcinoma (SGc), sebaceous cell carcinoma, and mebomian gland carcinoma is an uncommon and aggressive malignant cutaneous tumor. Most are typically about 10 mm in size at presentation. This neoplasm is thought to arise from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. Sebaceous carcinoma can be divided into 2 types: ocular and extraocular. Because the periocular region is rich in this type of gland, this region is a common site of origin. The cause of these lesions are, in the vast majority of cases, unknown. Occasional cases may be associated with Muir-Torre syndrome. Due to the rarity of this tumor and variability in clinical and histological presentation, SGc is often misdiagnosed as an inflammatory condition or a more common type of tumor. Sebaceous carcinoma, also known as sebaceous gland carcinoma (SGc), sebaceous cell carcinoma, and mebomian gland carcinoma is an uncommon and aggressive malignant cutaneous tumor. Most are typically about 10 mm in size at presentation. This neoplasm is thought to arise from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. Sebaceous carcinoma can be divided into 2 types: ocular and extraocular. Because the periocular region is rich in this type of gland, this region is a common site of origin. The cause of these lesions are, in the vast majority of cases, unknown. Occasional cases may be associated with Muir-Torre syndrome. Due to the rarity of this tumor and variability in clinical and histological presentation, SGc is often misdiagnosed as an inflammatory condition or a more common type of tumor. Currently the ocular SGc is commonly treated with wide surgical resection or Moh's micrographic surgery. This type of cancer usually has a poor prognosis because of a high rate of metastasis. Sebaceous carcinoma is a skin cancer of the sebum producing glands. It is predominantly seen in the head and neck region, representing 25% of all reported lesions in this area. The periocular region, which includes the meibomian gland, caruncle, gland of Zeis and eyebrow, is one of the most common sites in which SC is observed. The meibomian gland is a type of sebaceous gland that lines the upper and lower eyelids, and does not contain a follicle. The glands of Zeis contain the individual eyelash. The upper eyelid contains more meibomian glands than the lower eyelid and consequently, SGc is 2-3 times more common in the upper eyelid. Patients diagnosed with SGc most commonly present with a painless subcutaneous nodule. Other presentations include an irregular mass, pedunculated lesion or diffuse skin thickening. SGc in the periocular region presents as a heterogeneous rapidly growing, pink or yellow colored painless papule. The cell of origin is usually unknown. Sebaceous gland carcinoma clearly resembles normal sebaceous glands and is thought to arise from them. Ultraviolet and ionizing radiation are believed to play some role in the pathogenesis of these neoplasms. There is a strong association between Muir–Torre syndrome. There has been an association between the development of sebaceous carcinoma with the following: history of irradiation, immunosuppression, and genetic factors. One possible hypothesis states that stem cells in the hair follicle bulge and suprabasilar layer respond to different environmental stimuli, such as radiation, that may lead to the development of cutaneous tumors. Immunosuppressed individuals and those undergoing radiotherapy are at an increased risk for SGc. There has been some association between SGc and HIV, HPV (human papillomavirus) and mutations in tumor suppressor genes p53 and Rb. Rb mutations are responsible for retinoblastoma. Reports have also shown the onset of SGc within the field of irradiation for patients undergoing radiotherapy for retinoblastoma, eczema or cosmetic epilation. In addition to external factors, genes also appear to play some role in the pathogenesis of this tumor. Extraocular SGc is closely associated with Muir Torre syndrome (MTS), with sebaceous tumors presenting in nearly 1/3 of patients with MTS.