The hyperpigmentation, in contrast to melasma, often had blurry or ill-defined borders that seemed to fade into the patient's skin color.
Baltimore - A. Melvin Alexander, M.D., first noticed what he calls "maturational hyperpigmentation" - a mysterious disorder that predominantly affects blacks - when his brother, an otolaryngologist, developed it.
The disorder causes hyperpigmentation on the face, usually in the cheek areas. Dr. Alexander has also observed the disorder in individuals from India.
In fact, he saw several patients in his practice each week with the same hyperpigmentation on the malar and zygomatic facial areas. The hyperpigmentation, in contrast to melasma, often had blurry or ill-defined borders that seemed to fade into the patient's skin color. Although the discoloration was occasionally accompanied by itching, no patients in his practice sought medical help for it.
Biopsies showed melanocyte proliferation in the basal cell layer of the epidermis; features of post-inflammatory hyperpigmentation were absent.
Dr. Alexander noted another commonality among his patients with this peculiar disorder - they were all overweight. After deciding to find out more about maturational hyperpigmentation, he financed a study of eight patients after which he concluded that the entity was not uncommon, typically had onset in adulthood and was not initiated by any accidental trauma or injury.
"Most patients in the study did not have an allergy or a family history of the disorder," he says (Dermatology Times. 2006;27(1):32-33).
Dr. Alexander, in cooperation with his co-investigator, Dr. Janet Sloane, has just completed a larger follow-up study of the disorder, in which 20 patients answered detailed questions about their disorder.
The study has helped shed more light on this condition.
The results show some commonalities among the 20 subjects who have the disorder. Among the 16 females in the study with maturational hyperpigmentation, all but one (94 percent) showed a correlation between their preferred sleeping side and the side that exhibited the condition most prominently.
"This supported a theory we had that sleeping pressure might play a role in the disorder," Dr. Alexander says.
Among the four males in the study, two slept on the same side upon which their dermatosis was most developed.
"There was a correlation between sleeping side and the disorder's prominence in 17 (85 percent) of the 20 subjects," Dr. Alexander says.
In this second study, Dr. Alexander also obtained a number of lab tests. Of the 14 subjects who had blood drawn, seven (50 percent) had hyperglycemia and five (36 percent) showed hyperinsulinism. He also found that out of seven subjects who had alpha MSH levels tested - a measure of a melanocyte stimulating hormone that also reduces appetite - six (86 percent) had low levels of this hormone.
"This was a bit surprising in light of the melanocyte proliferation seen in the biopsies, but it did seem to be related to the weight of the subjects," Dr. Alexander says.
In the end, "The study raised more questions than answers," Dr. Alexander says.
Since all subjects were overweight and a substantial percentage had hyperglycemia and/or hyperinsulinism, Dr. Alexander notes that maturational hyperpigmentation may be a useful marker for diabetes or pre-diabetes.
To investigate this disorder further, Dr. Alexander hopes to secure grant funding for an even larger study.
He notes that these limited studies pose very interesting questions: