MedGen

Congenital melanocytic nevus syndrome is characterized by pigmentary skin defects apparent at birth. Most individuals have 1 or more large or giant lesions greater than 20 cm and up to over 60 cm in diameter, which may cover up to 80% of total body area. These lesions may or may not be hairy. Smaller 'satellite' pigmented lesions numbering in the hundreds may also be present all over the body. Congenital melanocytic nevi (CMN) can be associated with malignant melanoma (see CMM1, 155600), but the risk appears to be low, ranging from 1 to 2% for all individuals, but rising to 10 to 15% in those with very large nevi (greater than 40 cm). A small subset of patients with CMNS have abnormalities of the central nervous system, known as 'neurocutaneous melanosis' or 'neuromelanosis' (249400), which may be symptomatic. Patients with CMNS also tend to have a characteristic facial appearance, including wide or prominent forehead, periorbital fullness, small short nose with narrow nasal bridge, round face, full cheeks, prominent premaxilla, and everted lower lip (summary by Kinsler et al., 2008; Kinsler et al., 2012). Spitz nevi are benign melanocytic melanomas composed of epithelioid or spindle cell melanocytes. They usually present as solitary skin tumors but can occur in multiple patterns, having agminated, dermatomal, and disseminated forms (summary by Sarin et al., 2013). Nevus spilus, also known as speckled lentiginous nevus, is a congenital hyperpigmented patch that progressively evolves, with affected individuals developing dark macules and papules during childhood and adolescence. Over time, nevus spilus may give rise to common lentigines, melanocytic nevi, Spitz nevi, and melanomas (summary by Sarin et al., 2014). [from OMIM]

Subcutaneous bleeding with a diameter greater than 1 cm (ecchymosis). The bleeding does not extend into the tarsal plate (the comparatively thick, elongated plates of dense connective tissue within the eyelid) due to an anatomic structure called the orbital septum, which limits extravasation of blood beyond the tarsal plate. [from HPO]

A type of epilepsy that presents with typical absence seizures between 9 and 13 years of age in an otherwise normal adolescent. The typical absence seizures usually occur less than daily in the untreated state and are provoked by hyperventilation in 87 percent of cases. Generalized tonic-clonic seizures are seen in greater than 90 percent of cases, most commonly beginning shortly after onset of absence seizures. Myoclonic seizures do not occur. Development and cognition are typically normal. Neurological examination is normal. The electroencephalogram shows 3 to 5.5 Hz generalized spike-wave with a normal background. [from SNOMEDCT_US]

An uncommon neurovascular condition seen with exertion of the upper extremity. It is usually caused by atherosclerotic stenosis or occlusion of the subclavian artery proximal to the origin of the vertebral artery. In order to maintain adequate perfusion of the arm during exercise on the affected side, the narrowed subclavian artery siphons off retrograde blood flow from the ipsilateral vertebral artery. This is possible due to lower blood pressure distal to the site of narrowing and collateral circulation through the circle of Willis. Affected individuals may remain asymptomatic until the oxygen demand generated from upper extremity exercise requires a large enough compensatory volume of blood to be diverted from the vertebral artery to provoke vertebrobasilar insufficiency and its accompanying neurological sequelae. Presenting clinical signs may include pain or numbness of the affected arm (with diminished pulses and a brachial systolic blood pressure differential of greater than 20 mmHg as compared to the opposite arm), vertigo, tinnitus, dysarthria, diplopia and syncope. Notably, unlike cerebral infarction, the clinical course does not lead to chronic neurologic disability. Prognosis for recovery of normal anterograde circulation is favorable following endovascular or surgical intervention. [from NCI]