: 86 In conjunction with increased end levels of IGF, it is likely that perspiration and friction may be necessary predeterminants for lesions, since the level of insulin is usually not enough to activate IGF receptors across the body. Diagnosis
Acanthosis nigricans is typically diagnosed clinically. A skin biopsy may be needed in unusual cases. If no clear cause is obvious, it may be necessary to search for one. Blood tests, an endoscopy, or X-rays may be required to eliminate the possibility of diabetes or cancer as the cause. : 87 On biopsy, hyperkeratosis, epidermal folding, leukocyte infiltration, and melanocyte proliferation may be seen. : 979 : 87

Differential diagnosis
Acanthosis nigricans should be distinguished from the casal collar appearing in pellagra. Classification
Acanthosis nigricans is conventionally divided into benign and malignant forms, although may be divided into syndromes according to cause:: 506 
Benign This may include obesity-related, hereditary, and endocrine forms of acanthosis nigricans. Malignant. This may include forms that are associated with tumour products and insulin-like activity, or tumour necrosis factor.An alternate classification system still used to describe acanthosis nigricans was proposed in 1994. It delineates acanthosis nigricans syndromes according to their associated syndromes, including benign and malignant forms, forms associated with obesity and drugs, acral acanthosis nigricans, unilateral acanthosis nigricans, and mixed and syndromic forms. Treatment
People with acanthosis nigricans should be screened for diabetes and, although rare, cancer. Controlling blood glucose levels through exercise and diet often improves symptoms. Topical fade creams (normally used for eliminating age spots) can lighten skin cosmetically in less severe cases.
It occurs most frequently in those less than five years of age. The risk of death is about 25%. The diagnosis include retinal bleeds, multiple fractures of the long bones, and subdural hematomas (bleeding in the brain). These signs have evolved through the years as the accepted and recognized signs of child abuse. Medical professionals strongly suspect shaking as the cause of injuries when a young child presents with retinal bleed, fractures, soft tissue injuries, or subdural hematoma that cannot be explained by accidental trauma or other medical conditions.Retinal hemorrhage (bleeding) occurs in around 85% of SBS cases and the severity of retinal hemorrhage correlates with severity of head injury. The type of retinal bleeds are often believed to be particularly characteristic of this condition, making the finding useful in establishing the diagnosis.Fractures of the vertebrae, long bones, and ribs may also be associated with SBS. Dr. John Caffey reported in 1972 that metaphyseal avulsions (small fragments of bone torn off where the periosteum covering the bone and the cortical bone are tightly bound together) and "bones on both the proximal and distal sides of a single joint are affected, especially at the knee".Infants may display irritability, failure to thrive, alterations in eating patterns, lethargy, vomiting, seizures, bulging or tense fontanels (the soft spots on a babys head), increased size of the head, altered breathing, and dilated pupils.