Birt–Hogg–Dubé syndrome (BHD), also Hornstein–Birt–Hogg–Dubé syndrome, Hornstein–Knickenberg syndrome, and fibrofolliculomas with trichodiscomas and acrochordons is a human, adult onset, autosomal dominant genetic disorder caused by a mutation in the folliculin (FLCN) gene. It can cause susceptibility to kidney cancer, renal and pulmonary cysts, and noncancerous tumors of the hair follicles, called fibrofolliculomas. The symptoms seen in each family are unique, and can include any combination of the three symptoms. Fibrofolliculomas are the most common manifestation, found on the face and upper trunk in over 80% of people with BHD over the age of 40. Pulmonary cysts are equally common (84%) and 24% of people with BHD eventually experience a collapsed lung. Kidney tumors, both cancerous and benign, occur in 14–34% of people with BHD; the associated kidney cancers are often rare hybrid tumors.
Rasmussen syndrome is a condition characterized by multiple skin growths called trichoepitheliomas.
Keratoacanthoma (KA) is a common low-grade rapidly-growing skin tumour that is believed to originate from the hair follicle and can resemble squamous cell carcinoma.
Syringomas are benign eccrine sweat duct tumors, typically found clustered on eyelids, although they may also be found in the armpits, abdomen, chest, neck, scalp, or groin area, including genitals, in a symmetric pattern. They are skin-colored or yellowish firm, rounded bumps, 1–3 mm in diameter, and may be confused with xanthoma, milia, hidrocystoma, trichoepithelioma, and xanthelasma. They are more common in women and are most commonly found in middle-aged Asian women. While they can present at any time in life, they typically present during adolescence. They are usually not associated with any other symptoms, although can sometimes cause itchiness or irritation.
Nevoid basal-cell carcinoma syndrome (NBCCS) is a rare inherited medical condition involving defects within multiple body systems such as the skin, nervous system, eyes, endocrine system, and bones. People with NBCCS are prone to developing various cancers, including a common and usually non-life-threatening form of non-melanoma skin cancer called basal-cell carcinomas (BCCs). Only about 10% of people with the condition do not develop BCCs; the vast majority of patients develop numerous BCCs.
Muir–Torre syndrome is a rare hereditary, autosomal dominant cancer syndrome that is thought to be a subtype of HNPCC. Individuals are prone to develop cancers of the colon, genitourinary tract, and skin lesions, such as keratoacanthomas and sebaceous tumors. The genes affected are MLH1, MSH2, and more recently, MSH6, and are involved in DNA mismatch repair.
A mucinous neoplasm is an abnormal and excessive growth of tissue (neoplasia) with associated mucin. It arises from epithelial cells that line certain internal organs and skin, and produce mucin. A malignant mucinous neoplasm is called a mucinous carcinoma. For example, for ovarian mucinous tumors, approximately 75% are benign, 10% are borderline and 15% are malignant.
Rombo syndrome is a very rare genetic disorder characterized mainly by atrophoderma vermiculatum of the face, multiple milia, telangiectases, acral erythema, peripheral vasodilation with cyanosis, and a propensity to develop basal cell carcinomas.
Schöpf–Schulz–Passarge syndrome is an autosomal recessive condition with punctate symmetric palmoplantar keratoderma, with the keratoderma and fragility of the nails beginning around age 12. In addition to palmoplantar keratoderma, other symptoms include hypodontia, hypotrichosis, nail dystrophies, and eyelid cysts. Patients may also develop syringofibroadenoma and squamous cell carcinomas.
Sebaceous carcinoma, also known as sebaceous gland carcinoma (SGc), sebaceous cell carcinoma, and meibomian gland carcinoma, is an uncommon malignant cutaneous (skin) tumor. Most are typically about 1.4 cm at presentation. SGc originates from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. SGc can be divided into 2 types: periocular and extraocular. The periocular region is rich in sebaceous glands making it a common site of origin. The cause of these lesions in the vast majority of cases is unknown. Occasional cases may be associated with Muir-Torre syndrome. SGc accounts for approximately 0.7% of all skin cancers, and the incidence of SGc is highest in Caucasian, Asian, and Indian populations. 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 neoplasm. SGc is commonly treated with wide local excision or Mohs micrographic surgery, and the relative survival rates at 5 and 10 years are 92.72 and 86.98%, respectively.
Bazex–Dupré–Christol syndrome is a very rare condition inherited in an X-linked dominant fashion. Physical findings typically include follicular atrophoderma, multiple basal cell carcinomas, hypotrichosis, and hypohidrosis.
Giant solitary trichoepithelioma is a cutaneous condition characterized by a skin lesion that may be up to several centimetres in diameter.
Desmoplastic trichoepithelioma is a cutaneous condition characterized by a solitary, firm skin lesion on the face. Familial cases have been reported suggesting a possible genetic link.
Trichilemmoma is a benign cutaneous neoplasm that shows differentiation toward cells of the outer root sheath. The lesion is often seen in the face and neck region. Multifocal occurrence is associated with Cowden syndrome, in which hamartomatous intestinal polyposis is seen in conjunction with multiple tricholemmoma lesions.
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) or Reed's syndrome is rare autosomal dominant disorder associated with benign smooth muscle tumors and an increased risk of renal cell carcinoma. It is characterised by multiple cutaneous leiomyomas and, in women, uterine leiomyomas. It predisposes individuals to renal cell cancer, an association denominated hereditary leiomyomatosis and renal cell cancer. It is also associated with increased risk of uterine leiomyosarcoma. The syndrome is caused by a mutation in the fumarate hydratase gene, which leads to an accumulation of fumarate. The inheritance pattern is autosomal dominant and screening can typically begin in childhood.
Brooke–Fordyce syndrome is a condition characterized by multiple trichoepitheliomas.
CYLD cutaneous syndrome (CCS) encompasses three rare inherited cutaneous adnexal tumor syndromes: multiple familial trichoepithelioma (MFT1), Brooke–Spiegler syndrome (BSS), and familial cylindromatosis (FC). Cutaneous adnexal tumors are a large group of skin tumors that consist of tissues that have differentiated towards one of the four primary adnexal structures found in normal skin: hair follicles, sebaceous sweat glands, apocrine sweat glands, and eccrine sweat glands. CCS tumors are hair follicle tumors.
