The melanocytic tumours in these cases are thought to relate to the same genetic errors in the development of the embryonic neural tube that lead to the DWM, since the subsequent embryonic neural crest gives rise to melanocytes, among other cells. 10% of patients had endocrine or metabolic disorders, and 2.7% had excessive hair growth (hypertrichosis). 9% of patients (almost all with classic DWM) had musculoskeletal abnormalities, which included scoliosis or kyphoscoliosis and arthrogryposis. 5.9% of patients had underdeveloped reproductive organs, such as hypoplastic genitalia or undescended testicles (cryptorchidism). 5.3% of patients had underdeveloped or polycystic kidneys.Occipital encephalocele may occur in DWM. This has generally been found at rates between 6 and 8%. It has been suggested to occur to compensate for the increased pressure in the posterior fossa during foetal life.Syringomyelia occasionally occurs with DWM, though it is not certain how often. One review reported an occurrence of 4.3% in a sample. This may be due to herniation of the bottom of the cyst through the foramen magnum (a similar mechanism to Chiari malformation). Alternatively, it may be a result of hydrocephalus, in which it forms as a "fifth ventricle" due to an enlarged central canal.Rarely, spina bifida has been found with DWM. When it is present, it is usually spina bifida occulta. Cause
DWM is caused by any disruption to embryonic development that affects the formation of the cerebellar vermis. This is usually a genetic mutation that results in impaired cell migration and division. A large number of genetic conditions can result in the anomaly.
Factitious dermatitis, also known as dermatitis artefacta, is a form of factitious disorder in which patients will intentionally feign symptoms and produce signs of disease in an attempt to assume the patient role. It is also self-inflicted skin damage, most commonly from prolonged deliberate scratching, but sometimes by means of sharp instruments or another agency. : 391 : 61

See also
List of cutaneous conditions

References


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