A 43-year-old African-American man presents with a six-year history of a worsening, asymptomatic skin condition. He has been evaluated by dermatology in the past, and in 2001 he was treated with minocycline. This medication triggered a lupus-like reaction from which the patient almost died. Needless to say, the treatment was stopped, but the condition continues to worsen.

Other than having diet-controlled diabetes and being obese, the patient is healthy, with no continuous medication use during the course of his skin condition. There is no seasonality to the condition, and the patient denies any concurrent skin problems. Just prior to this referral to dermatology, the patient was treated with terbinafine, to no good effect.

On examination, the first thing noted is the broad macular band of brownish hyperpigmentation across the patient’s forehead. The darkening on his neck and chest, also macular, has a distinctly reticular pattern to it. What little scale there is proves to be KOH negative. The axillae and other intertriginous areas are totally spared.

ANSWER
The correct answer is choice “b.” Terbinafine belongs to a class of antifungals called the allylamines, which are quite effective against dermatophytes but are relatively ineffective against the organisms that cause tinea versicolor—almost certainly the diagnosis the prescriber had in mind. Therefore, “b” is an incorrect statement.

DISCUSSION/TREATMENT
Hyperpigmentation has many potential causes, including acanthosis nigricans. However, that condition would not demonstrate the distinctly reticular pattern seen in this patient and would almost certainly have also involved the axillae and groin. Lupus was also worth considering, since it is well known to disrupt pigmentation on darker-skinned patients, and biopsy is the only sure way to rule it out.

Tinea versicolor was quite unlikely, given the reticular pattern and negative KOH. Moreover, tinea versicolor is very predictably seasonal, blossoming with the advent of hot weather and fading in the fall and winter.

This case highlights the issue of dyschromia, an extremely common complaint in darker-skinned patients. Fortunately, as noted above, the history and appearance were helpful in narrowing the diagnostic choices. The punch biopsy confirmed the clinical impression of an unusual condition called “confluent and reticulated papillomatosis [CRP] of Gougerot and Carteaud.” It was first reported in 1927, and a number of potential causes have been postulated. Obviously, the biopsy also ruled out the other items in the differential, most notably lupus.

CRP was quite possibly the diagnosis made in 2001 that was treated with minocycline with near-disastrous results. The latest theory to arise as to its cause is that it represents an abnormal reaction to an otherwise minor bacterial infection of hair follicles with a species of actinomycetes. This might account for the success of antibiotics such as those from the tetracycline family and the macrolides. Indeed, this patient was successfully treated with a month-long course of oral erythromycin (400 mg tid).