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Genetic conditions can predispose at risk individuals to develop internal malignancy. These conditions can broadly be classified into four types:
  1. Primary immunodeficiency
  2. Gastrointestinal polyposis
  3. Chromosomal instability
  4. Others
  1. In primary immunodeficiency, a. patients are more susceptible to infections as well as the development of haematological malignancy.
  2. associated features b. cerebellar ataxia, as seen in ataxia telangiectasia, or eczema as in the case of Wiskott-Aldrich syndrome. c. Other conditions in this category include severe combined immunodeficiency and Burton's agammagloblinemia.
    1. A group of genodermatoses have in common gastrointestinal harmartoma, cutaneous signs and internal neoplasm.
    2. The more commonly known of these conditions include Gardner's and Peutz-Jeghers. Gardner's syndrome is an autosomal dominant condition may present in childhood as multiple benign skin tumour, such as lipoma or fibroma.
    3. When these patients reach the third to fourth decades, they develop large bowel polyps which are usually thought to turn malignant later in life.
  3. Peutz-Jeghers syndrome is also dominant in inheritance and patients presented with lentigo in the perioral area as well as bowel hamartoma. Intestinal obstruction can occur.
  4. These patients have an increase risk of developing non-gastrointestinal tract tumours that include bronchial and breast carcinoma. The risk of developing gastrointestinal tract tumour is also increase. Other syndromes that are classified into the same category as Peutz-Jeghers include Cowden¡¦s disease, Muir-Torre syndrome, Howel-Evans syndrome and Multiple endocrine neoplasm type III.
  5. Conditions are associated with chromosomal instability as a result of which excessive DNA damage can occur leading to an increase risk of internal malignancy.
  6. This group of conditions include Bloom's syndrome, Werner's syndrome, Fanconi's anaemia and Dyskeratosis congenita.
  7. Genodermatoses that associated with internal malignancy.
    These include neurofibromatosis, haemochromatosis and Gorlin's syndrome.
    1. Neurofibromatosis is relatively common. It is inherited as an autosommal dominant condition and is known to be associated with malignant schwannoma, phaeochromocytoma and carcinoid tumour.
    2. Hepatocellular carcinoma can occur in haemochromatosis especially in elderly male with cirrhosis.
    3. Gorlin's syndrome affects young patient with multiple basal cell carcinomas, odontogenic cysts and skeletal abnormalities. Medulloblastoma is a known association.
    4. Neurofibromatosis

      Neurofibromatosis (NF) is one of the most common neurocutaneous conditions and consists of eight distinct forms of neurofibromatosis. The first two types are the most common and are autosomal dominant disorders with somewhat overlapping features: neurofibromatosis type 1, also referred to as von Recklinghausen's disease, and the less common NF type 2.
  8. Neurofibromatosis type I (NF-1)
    NF-1 is one of the most common autosomal dominant disorders in humans.
    NF-1 accounts for 96% to 97% of ail cases of NF and results from defects in the NF-1 gene on chromosome 17
  9. Clinical features and presentation
    For NF-1, the diagnostic criteria are met if two or more of the following features listed are present:
    1. Six or more cafe au lait (CAL) macules greater than 5 mm in prepubertal patients and greater than 15 mm in postpubertal patients;
    2. Two or more neurofibromas of any type, or one plexiform neurofibroma;
    3. Axillary or inguinal freckling;
    4. Optic nerve glioma;
    5. Two or more Lisch nodules (iris hamartomas);
    6. A distinctive osseus lesion such as sphenoid wing dysplasia or cortical thinning of long bones, with or without pseudoarthrosis; and
    7. A first-degree relative with NF-1 based on the preceding criteria.
      CAL macies typically appear either at birth or during the first few years of an affected person's life. When
      1. In patients with NF-1, the most common benign tumor is a neurofibroma, which may be cither circumscribed (cutaneous or subcutaneous) or non-drcumscribed (plexiform).
      2. For women, neurofibromas occur in almost 90% in the periareolar location; thus, breast examination is one of the best ways to detect subtle disease in an adult woman.
      3. Plexiform neurofibromas can wrap in and around vital structures and cause pronounced disfigurement, including compromised hearing.
      4. These arc specific for NF-1 Optic nerve glioma is estimated to occur in 15% of patients with NF-1.
      5. Although these tumors usually develop by the lime the patient is 10 years old, symptoms of proplosis, decreased visual acuity, or precocious puberty (caused by pituitary compression) may not occur until years later. Treatment of optic nerve gliomas is often surgical and results in loss of vision; chemotherapeutic management is being investigated.
      6. Lisch nodules are iris harmatomas.
      7. Early development of Lisch nodules will be delectable with careful examination under a slit lamp by the age of 6 years.
      8. Distinctive osseus lesions of NF-1 include sphenoid wing dysplasia, which often results in pulsating exophthalmos or pseudoarthrosis of the tibia or fibula.
      9. This can predipose individuals to pathologic fractures and false joint formation.

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