National trends in ambulance use by patients with stroke, 1997-2008.

tion, the differential diagnosis may also include a number of other conditions such as lichen sclerosus, psoriasis, discoid lupus, graft-vs-host disease, and secondary syphilis. The intention of our article was to provide a clear and concise introduction to lichenoid drug eruption, rather than dwell on the subtleties of the differential diagnosis. We agree that in cases in which the clinical diagnosis “was so clinically clear that no other diagnosis was considered,” there is little point in subjecting a patient to a skin biopsy. We would go 1 step further to recommend that a biopsy not be performed unless the results could alter clinical management. However, when considering inflammatory dermatoses (including lichenoid drug eruption) with overlapping clinical patterns and divergent treatment approaches, the skin biopsy is of tremendous importance in reaching an accurate diagnosis, especially when performed by a dermatologist. With respect to our patient, we would have recommended discontinuation of lisinopril with every differential diagnosis. However, our definitive diagnosis allowed us to (1) more accurately counsel the patient regarding the expected time course and resolution of her eruption, (2) advise her of potential associated symptoms, (3) recommend alternative antihypertensives that are not likely to induce her particular eruption, and (4) have a treatment plan in place in the event that her eruption failed to resolve or worsened. In general, a biopsy early in the clinical course of an eruption—and prior to any physicianor patient-initiated treatment—provides the most definitive, accurate, and cost-effective result. Finally, although our patient’s history was relatively straightforward and lent itself well to the teaching purposes of the article, most cases are not so clear-cut. Lichenoid drug eruptions have an extremely variable latency period (from weeks to years) and can be induced by numerous medications. It is frequently much more difficult to determine whether the eruption is drug-induced than it was in this case. In addition, the discontinuation of a potential culprit medication may have much more serious implications for the patient. As discussed in the article, histological features are often helpful in differentiating idiopathic lichen planus from lichenoid drug eruption.