Synonyms for fibrofolliculomas or Related words with fibrofolliculomas


Examples of "fibrofolliculomas"
Birt–Hogg–Dubé syndrome can manifest similarly to other diseases, which must be ruled out when making a diagnosis. These include tuberous sclerosis, which causes skin lesions similar to fibrofolliculomas, and Von Hippel-Lindau disease, which causes hereditary kidney cancers. Once diagnosed, people with BHD are treated preventatively, with monitoring of kidneys and lungs using medical imaging. Fibrofolliculomas can be removed surgically and pneumothorax and kidney cancer are treated according to the normal standard of care.
Fibrofolliculomas are 2 to 4 mm in diameter, dome-shaped, yellowish or skin-colored papules usually located on the head, neck, and upper trunk. They are characteristically seen in Birt–Hogg–Dubé syndrome.
Birt–Hogg–Dubé syndrome (BHD), also Hornstein–Birt–Hogg–Dubé syndrome, Hornstein–Knickenberg syndrome, and fibrofolliculomas with trichodiscomas and acrochordons is a human autosomal dominant genetic disorder that 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%), but only 24% of people with BHD eventually experience a collapsed lung (spontaneous pneumothorax). Kidney tumors, both cancerous and benign, occur in 14–34% of people with BHD; the associated kidney cancers are often rare hybrid tumors.
Other tumors can include trichodiscomas (tumors of the hair disc, which may be identical to fibrofolliculomas), angiofibromas, and perifollicular fibromas. However, angiofibromas are more common in tuberous sclerosis. Along with the tumors, other skin conditions are seen in people with Birt–Hogg–Dubé syndrome. Approximately 40% of people or families with the disease have papules in their mouth, which can be located on the cheeks (buccal mucosa), tongue, gums, or lips. Either white or mucosa-colored, they are discrete, small, and soft and consist of fibrous tissue covered in thickened epithelium. Collagenomas of the skin are also found in some families. Many people with BHD have skin lesions that appear to be acrochordons (skin tags), but may instead be fibrofolliculomas. These lesions are usually found in the armpit, on the eyelids, and in folds of skin. Not all individuals develop the facial tumors; some families with the mutation that causes BHD develop only kidney tumors or spontaneous pneumothorax.
Birt–Hogg–Dubé syndrome affects the skin and increases the risk of tumors in the kidneys and lungs. The condition is characterized by multiple noncancerous dome-shaped tumors of the hair follicles (fibrofolliculomas), particularly on the face, neck, and—more rarely—the upper chest. The fibrofolliculomas are generally described as having an opaque white color or a yellowish tone and have a waxy, smooth texture. The tumors are always found on and around the nose and on and behind the outer ear. Typically, they first appear in a person's 20s or 30s, and are found in more than 80% of people with the syndrome above the age of 40. The tumors become larger and more numerous over time. Tumors differ between individuals: they may appear merged in plaques, look similar to a comedo with a plug of keratin, or include epidermoid cysts. A large number of tumors on the face can be associated with hyperseborrhea (abnormally elevated sebum production). The presence of fibrofolliculomas on a person's face can cause significant psychological distress.
The earliest case of possible BHD in the medical literature was published by Burnier and Rejsek in 1927, who described a case of perifollicular fibromas on a 56-year-old woman's face. Trichodiscomas were first described in 1974 by H.S. Zackheim and H. Pinkus, but were not associated with BHD until Birt, Hogg, and Dubé. The first case of BHD with the systemic symptoms was described by Hornstein and Knickenberg and found in two siblings and their father, all of whom exhibited colon polyps and the characteristic fibrofolliculomas. Though the siblings did not have renal or pulmonary symptoms, their father had cysts in his lungs and kidneys. Hornstein-Knickenberg syndrome is a now-deprecated name for the inherited fibrofolliculomas inherent to Birt–Hogg–Dubé.
Though fibrofolliculomas are unique to Birt–Hogg–Dubé, they may present with an ambiguous appearance and must be confirmed histologically. Other diseases can mimic the dermatologic manifestations of BHD, including tuberous sclerosis complex, Cowden syndrome, familial trichoepitheliomas, and multiple endocrine neoplasia type 1. Tuberous sclerosis must be distinguished because both disorders can present with angiofibromas on the face, though they are more common in tuberous sclerosis.
Birt, Hogg, and Dubé examined a family with a hereditary thyroid cancer and discovered that many of the members had fibrofolliculomas, trichodiscomas, and acrochordons, which became defined as the classical symptoms of the eponymous disease. The first case of spontaneous pneumothorax associated with BHD was discovered in 1986; the first case of renal cancer followed in 1993 and the presence of lung cysts in people with BHD was confirmed in 1999. It was formerly thought that people with Birt–Hogg–Dubé syndrome were at higher risk for colorectal polyps and neoplasms, but this has been disproven. The BHD Foundation supports research into the syndrome and holds regular symposia in BHD and related disorders for researchers, clinicians, and family members.
The cutaneous manifestations of Birt–Hogg–Dubé were originally described as fibrofolliculomas (abnormal growths of a hair follicle), trichodiscomas (hamartomatous lesions with a hair follicle at the periphery, often found on the face), and acrochordons (skin tags). Cutaneous manifestations are confirmed by histology. Most individuals (89%) with BHD are found to have multiple cysts in both lungs, and 24% have had one or more episodes of pneumothorax. The cysts can be detected by chest CT scan. Renal tumors can manifest as multiple types of renal cell carcinoma, but certain pathological subtypes (including chromophobe, oncocytoma, and oncocytic hybrid tumors) are more commonly seen. Although the original syndrome was discovered on the basis of cutaneous findings, it is now recognized that individuals with Birt–Hogg–Dubé may only manifest the pulmonary and/or renal findings, without any skin lesions. Though these signs indicate BHD, it is only confirmed with a genetic test for FLCN mutations.
Along with fibrofolliculomas and kidney tumors, affected individuals frequently develop cysts (blebs or bullae) in the subpleural lung base or intraparenchymal space that may rupture and cause an abnormal collection of air in the chest cavity (pneumothorax), which could result in the collapse of a lung. The cysts do not cause other symptoms and lung function is usually normal. More than 83% of people with Birt–Hogg–Dubé have cysts, however, the syndrome does not cause conditions like progressive chronic obstructive pulmonary disease (COPD) or generalized respiratory failure, though it does cause emphysema. Spontaneous, sometimes recurrent, pneumothorax occurs far more often and at a younger age with Birt–Hogg–Dubé than in the unaffected population. Approximately 24% of people with the disease suffer at least one spontaneous pneumothorax, 30 times the occurrence in unaffected people. Though pneumothorax caused by Birt–Hogg–Dubé often occurs in middle age, at a median age of 38, 17% of affected people have a spontaneous pneumothorax before turning 40. Pneumothoraces have been seen in people as young as 7 and 16 years of age. Some families have a form of BHD that only affects the lungs.
People with Birt–Hogg–Dubé syndrome are born with one mutated copy of the FLCN gene in each cell. Haploinsufficiency—only having one functional copy of the FLCN gene—is enough to cause the fibrofolliculomas and pulmonary cysts, however, one copy of the gene is enough to keep kidney cells in check. During their lifetime, random mutations might inactivate the normal copy of the gene in a subset of cells. When this occurs, the result is that these cells have no functional copies of the FLCN gene, allowing the cells grow out of control. This loss of heterozygosity is a common mechanism in cancer, and it is frequently detected in the renal cancers associated with BHD. The molecular genetic defects in renal tumors of people with BHD are different from two other similar kidney tumors, chromophobe renal cell carcinoma and renal oncocytoma. BHD-associated tumorigenesis differs between the kidney, where loss of FLCN heterozygosity is responsible for cancers, and the skin, where FLCN is strongly expressed in heterozygotes. FLCN has been found to be overexpressed in fibrofolliculoma tissue and to have very low levels of expression in affected kidneys. Furthermore, the mTOR pathway is shown to be activated in tumor tissue from both humans and mice.
The different manifestations of Birt–Hogg–Dubé syndrome are controlled in different ways. The fibrofolliculomas can be removed surgically, through curettage, shave excision, skin resurfacing, or laser ablation; however, this is not a permanent solution as the tumors often recur. The renal and pulmonary symptoms are managed preventatively: CT scans, ultrasounds, or MRIs of the kidneys are recommended regularly, and family members are advised not to smoke. MRIs are the preferred method for surveillance of the kidneys in people with BHD because they do not carry the same risk of radiation complications as CT scans and are more sensitive than ultrasounds. Smokers with Birt–Hogg–Dubé have more severe pulmonary symptoms than non-smokers. Though nephrectomy is sometimes indicated, kidney tumors in cases of Birt–Hogg–Dubé are often removed without taking the whole kidney, in a procedure called partial nephrectomy. Knockout mouse studies have shown that administration of rapamycin may mitigate the effects of FLCN mutations on kidneys and improve renal cancer prognoses because of folliculin's interaction with the mTOR pathway.