History

A 78-year-old man presented with thickened, heavily lined skin on his posterior neck that had been present for an indeterminate period of time. Although the striking skin changes were asymptomatic, they were concerning to his relatives who insisted that he be seen by a dermatology provider.

The patient had spent nearly his whole life in the sun, farming, ranching, fishing, and tending to his property in rural Oklahoma. He denied a history of skin cancer and claimed to be in good health.

Physical Examination

The skin on the patient’s nuchal area was heavily lined and thickened. The lines joined to form multiple overlapping rhomboidal shapes. Although the color of the affected area was normal, the skin felt quite thick and inflexible. These skin changes stopped abruptly at the collar line, below which the skin was entirely normal.

Abundant evidence of sun damage — including weathering, telangiectasias, solar lentiginosis, and numerous actinic keratoses on prominent areas of his cheeks and ears — was noted. Similar changes were noted on the dorsa of both hands but were not present on his arms and trunk because he wore long-sleeved shirts when in the sun. Although he had worn a wide-brimmed hat while in the sun during his adult life, he had never worn anything, such as a bandana, on his neck.

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Diagnosis

The posterior neck is especially susceptible to the effects of the sun, evidence of which frequently manifests as it did in this patient. This condition is called cutis rhomboidalis nuchae (CRN), which represents thickening and weathering of the epidermis as well as solar elastosis of the underlying dermis caused by the sun. Although this condition is clear evidence of chronic overexposure to the sun, CRN has no malignant potential, and treatment is neither required nor does it exist.

Besides being common, CRN is unique in its presentation, as well as in the patient population it affects (eg, older patients with sun damage confined to the posterior neck), so the differential is quite narrow. Punch biopsy would resolve any confusion.

CRN puts this patient at higher risk for the development of skin cancers caused by sun exposure, such as basal cell carcinoma, squamous cell carcinoma, melanoma, and others. This patient and others with similar histories require regular skin checks by a qualified dermatology provider at least once a year. Although this patient would be advised to protect himself from the sun, this will do little to ward off any future skin cancers that will have been caused by sun overexposure occurring decades earlier. Application of sunscreen to his neck would prevent worsening of his CRN.

Reference

Bolognia JL, Jorizzo JL, Rapini RP. Dermatology. 1st ed. New York: Mosby, 2003;1380-1381.