Connective Tissue Nevus

Key Points
Uncommon condition in which deeper layers of the skin experience an excess of collagen
Exact cause is unknown, but thought to be due to genetic defect of the skin cells
Cutaneous presentation varies between the two different subtypes: shagreen patches and Familial cutaneous Collagenoma (FCC)

Collagenoma, a type of Connective tissue nevus, is an rare condition in which the cells in the deeper layers of the skin experience an excess of collagen. There are two subtypes of collagenoma: shagreen patches and familial cutaneous Collagenoma (FCC). Shagreen patches consist of lesions on the nape of the neck and lower back with an orange peel-like texture. Lesions can be of varying size. FCC consists of multiple nodules over the upper back, which are hard and vary in size.

While the cause of Collagenoma is unknown, it is thought that it and other connective tissue nevi are due to genetic defect in the skin cells, though they may be attributed to an underlying condition. In any case, the condition is very rare. FCC generally presents during adolescence, and is occasionally related to heart disease. Shagreen patches are most often associated with Tuberous sclerosis.

Differential Diagnosis (Other conditions with similar appearance)

Elastofibroma
Granuloma faciale
Lichen Sclerosus et Atrophicus
Nephrogenic fibrosing dermopathy

Diagnosis
Key Points
Diagnosis based on skin appearance
Lab tests may be performed to rule out associated conditions

Collagenoma, and other connective tissue nevi, are generally diagnosed by appearance of the affected area. If an underlying associated condition is suspected, laboratory tests may be performed to diagnose the associated condition.

Treatment
Unassociated instances of the condition do not require treatment
*When associated with an underlying condition, health care professionals will treat that condition

Isolated Collagenoma, which indicates it is unrelated to another underlying condition, does not require treatment. If the condition is due to an associated disease, treatment will be for the disease and not the Collagenoma.