• Monday May 25,2020

Capel Knickenberg syndrome

Hornstein-Knickenberg syndrome is a genetic disorder associated with a mutation of elements of the mTOR signaling pathway. Because this chain of signals affects the growth and mortality of cells, a mutation manifests in multiple cell proliferations. The tumors express themselves as a multi-system disease.

What is the Hornstein-Knickenberg syndrome?

The cause of the Hornstein-Knickenberg syndrome seems to be genetics. A gender preference could not be observed.
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The Hornstein-Knickenberg syndrome was first described in the 20th century by the German dermatology professor Otto P. Hornstein and assistant Monika Knickenberg. In honor of the first authors, the complex of symptoms described by them was called the Hornstein-Knickenberg syndrome.

Because the symptom complex was described months later by Arthur R. Birt, W. James Dubé and Georgina R. Hogg, the clinical term Birt-Hogg-Dubé syndrome is a common synonym for the disease. Because it is a rare fibroma, the syndrome is also referred to as fibromatosis cutis. The symptoms of the disease manifest in adulthood, although the disease is considered a genetic and therefore congenital disease.

The incidence of the disease has not been clarified. However, the prevalence is estimated at around one case to be 200, 000. According to these estimates, the syndrome would be more common than some other genetic diseases. In the broadest sense, the syndrome can be classified as tumorous disease, as the affected individuals develop multiple and histologically distinct papules on the skin and organs. So far, the syndrome has been described on around 100 families.


The cause of the Hornstein-Knickenberg syndrome seems to be genetics. A gender preference could not be observed. The symptom complex has also been described as hereditary, familial or sporadic. In cases of familial clustering, autosomal dominant inheritance has been observed. The exact causes of the onset of symptoms are not fully understood.

However, there are a lot of speculations. The most likely is based on causative mutations in the FLCN gene on gene locus 17p11.2. This gene encodes DNA for the protein folliculin. The function of this endogenous substance is not yet known. However, there are assumptions that folliculin is an element of the mTOR signaling chain. This is the so-called mammalian Target Of Rapamycin.

This signaling chain has been proven to be crucial for cell survival, cell growth and cell mortality. In a mutation of the FLCN gene, the folliculin protein is defective. If, as speculated, it actually represents an element of the mTOR signaling chain, the mutation within that signaling chain could explain the excess cell growth and thus the symptomatic growths of the Hornstein-Knickenberg syndrome.

Symptoms, complaints & signs

Hornstein-Knickenberg syndrome is characterized by various clinical features. From about the age of fourteen, patients usually suffer from skin-colored to flesh-colored, waxy skin lesions that are up to five millimeters in size, hemispherical and usually asymptomatic.

In addition to dermal lesions, oral papules also occur. Histologically, the multiple lesions correspond to combinations of different structures. In addition to perifollicular fibroids of the trunk and head area, oscillating fibroids in the inguinal region, in the armpits or near the neck are common symptoms. In addition, there are usually adenomatous colon polyps. Tumors of the hair disc, lipomas, angiolipomas and basal cell carcinoma] may fit as well as the connective tissue nevus.

In addition to the dermal manifestations, the disease can also manifest in organic manifestations. The organ system often attacks them with symptoms such as colon carcinomas or adenomas, prostate carcinomas, renal cysts, angiolipomas or hyperuricemia. Emphysema of the lungs may also occur. Dasselne applies to bronchiectasis, hamartomas or pulmonary cysts.

In the eye area there is often retinopathy, chorioretinopathy or glaucoma. The endocrine system of the patients may be affected by thyroid carcinoma and parathyroid adenomas. With regard to the endocrine system, hypothyroidism or diabetes may also occur. In addition, hypertonia of the muscles, facial paralysis, progressive deafness, or aplasia of the arteries can also accompany the clinical picture.

Diagnosis & disease course

The first step in diagnosing Hornstein-Knickenberg syndrome is to identify all clinical manifestations and findings as symptoms of the same disease. If the symptoms are detected by imaging and the doctor has identified the manifestations of a syndrome, he can confirm the suspected diagnosis of the Hornstein-Knickenberg syndrome by demonstrating the mutations in the FLCN gene. The prognosis depends on the time of diagnosis, the involvement of internal organs and the type of tumors in individual cases.


Hornstein-Knickenberg syndrome causes cell proliferation. These generally have a very negative impact on the health of the patient. As a rule, it comes to skin lesions, which, however, do not lead to any special symptoms. The sufferer also suffers from fibroids and tumors in different regions of the body.

The internal organs can also be affected, so that without treatment usually comes to the death of the patient. Not infrequently, the eyes are affected by the Hornstein-Knickenberg syndrome, glaucoma may occur. Furthermore, most patients suffer from diabetes and deafness. Deafness is progressing and, as a rule, develops in the course of a disease.

It is not possible to causally treat the Hornstein-Knickenberg syndrome. For this reason, only the symptoms and symptoms of the syndrome can be limited and treated. Although there are no complications, a positive course of the disease can not be guaranteed. In some cases, this limits the life expectancy of the patient. Patients also need psychological counseling in most cases to relieve mental health problems.

When should you go to the doctor?

If skin lesions and oral papules are suddenly detected, it may well be due to the Hornstein-Knickenberg syndrome. A visit to a doctor is indicated if the symptoms persist for an extended period of time or if further symptoms occur. Typical of the disease is that it occurs from the fourth decade of life. Most of the symptoms increase over the years and ultimately cause emotional distress. The genetic defect must be promptly examined and treated by a general practitioner or dermatologist. Otherwise, serious complications may develop.

At the latest, when the characteristic tumors of the hair disc are noticed, medical advice is required. In case of visual disturbances, the ophthalmologist is best switched on. Organ diseases require clarification by a specialist in internal diseases. People who already have diabetes or numbness should inform the doctor about unusual symptoms and adjust their diet in cooperation with a nutritionist. Comprehensive medical treatment, supported by self-help measures, can help reduce symptoms of chert bone syndrome.

Treatment & Therapy

A causal therapy does not exist for patients of the Hornstein-Knickenberg syndrome as long as gene therapy measures are not permitted. Treatment is currently symptomatic and supportive for this reason. The dermatological manifestations of the syndrome can not be specifically treated. Manifestations such as the politically perifollicular fibroma are removed surgically.

Therapeutically, in the past also electro-desiccation and dermabrasion were discussed, which, however, are often associated with recurrences. If there are already manifestations in the organ system, these manifestations must also be surgically or microsurgically removed and, if necessary, post-treated. Close-meshed checkups are always indicated for patients with Hornstein-Knickenberg syndrome.

In this way, especially attacks on the organ system should be recognized in time. Supportive patients are usually proposed psychotherapeutic care. In addition to this step, those affected receive genetic counseling and are informed in this consultation, especially on the risk of disease of planned children and similar relationships.

Outlook & Forecast

Prognosis and outlook are based, among other things, on the time of diagnosis, the type and number of tumors and the extent of the disease. If the internal organs are involved, the prognosis is much more negative than with a pure infestation of the skin and other external organs. Basically, there is the prospect of a cure inasmuch as the disease is recognized early and treated. Patients must undergo chemotherapy or radiotherapy, which may cause further physical discomfort. However, complications can be reduced by optimally adjusted medication and comprehensive aftercare.

If the Hornstein-Knickenberg syndrome is detected late, the prognosis is poor. Then internal organs may already be affected and operations and other measures must be taken that are not always successful. However, there is always the chance of a complete recovery in the case of the Hornstein-Knickenberg syndrome. The patient must be treated early and also comply with the medical requirements. When recurrences develop, the chances of recovery decrease proportionally. Life expectancy is not necessarily limited by the Hornstein-Knickenberg syndrome.

The quality of life, on the other hand, is greatly reduced, since the multisystem illness affects the entire body and causes many-sided complaints. Painkillers and surgery can improve well-being in the long term. Nevertheless, a complete recovery is unlikely, so Hornstein-Knickenberg syndrome conclusively does not provide a good prognosis.


The Hornstein-Knickenberg syndrome can hardly be prevented so far. Since a hereditary basis is suspected, the only preventive measure is to renounce own children, if the syndrome is already known within their own family.


In the case of the Hornstein-Knickenberg syndrome, the patient has in most cases no or very few measures of direct follow-up care available. In case of this disease, a doctor must be consulted immediately so that there are no further complications or, in the worst case, death of the person affected. If the syndrome is not detected early and treated by a doctor, it can lead to the spread of the tumors.

Therefore, the patient should consult a doctor at the first symptoms and signs of the disease to prevent further discomfort. The complaints themselves are usually alleviated by surgery. In doing so, the patient should definitely rest after such an intervention and protect the body.

Efforts or stressful, physical activities should definitely be foreseen in order not to burden the body unnecessarily. Furthermore, regular examinations by a doctor are also very useful for the early detection and treatment of new tumors. It may be due to the Hornstein-Knickenberg syndrome to a reduced life expectancy of the patient. Since the syndrome can also lead to mental upset or depression, conversations with friends or family often make sense to prevent them.

You can do that yourself

Unfortunately, the possibilities of self-help in the Hornstein-Knickenberg syndrome are relatively limited, so that the person concerned is primarily dependent on medical treatment to relieve the symptoms.

In the case of diabetes, a strict diet must be followed to avoid further complications and discomfort. Here, a nutritionist can be consulted, who can create a nutrition plan for the person affected. The complaints in the eyes can usually be compensated by different visual aids. Furthermore, the use of nourishing creams and ointments can have a very positive effect on the skin complaints in the Hornstein-Knickenberg syndrome and relieve them. However, those affected need surgery to effectively fight the disease.

Psychological care continues to have a positive effect on the course of the disease. This care does not necessarily have to be done by a psychologist. Friends and relatives can contribute to the mental stability of the patient and relieve depression. Especially in children, a clarifying conversation about the possible course of the disease should be carried out. Furthermore, sufferers should undergo genetic counseling to avoid the chert-Knickenberg syndrome in children.

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