funDERMentals
DISCUSSION
Based on the appearance of the lesions, the patient’s family history, and the histopathologic findings, a diagnosis of necrobiosis lipoidica (NL) was made. When NL was first described in 1929, it was only seen in diabetic persons and thus was named necrobiosis lipoidica diabeticorum. By 1932, however, cases of NL were being reported in persons without diabetes—so the “diabeticorum” was dropped.
Only 0.3% of diabetic persons develop NL. In 15% of cases, NL precedes diabetes; in 60%, diabetes manifests first. Simultaneous diagnosis of both occurs about 25% of the time.
The cause of NL is still unknown. Most theories suggest it is related in some way to diabetes, since most persons with NL have a personal or family history of diabetes or register abnormal results to glucose tolerance testing. Furthermore, the microvascular changes seen in NL lesions are reminiscent of those seen in microangiopathic lesions in diabetic patients. Oddly enough, though, the presence or progression of NL does not correlate with how well controlled the patient’s diabetes is.
Other theories center on an autoimmune mechanism, based on demonstrable deposition of immunoglobulins, components of complement, and fibrinogen in vessel walls. High levels of TNF-a are found in many cases of NL, a fact that researchers are pursuing vigorously.
NL can manifest anywhere but is most common on the legs, where 75% of patients report no symptoms beyond a slight loss of sensation. The remaining 25% do report moderate to severe pain.
In terms of diagnosis, the appearance and history are sufficient in most cases. In this particular case, the lesions were fairly new and small, and the differential thus included such worrisome items as sarcoidosis or even Hansen’s disease. Less concerning differential items included granuloma annulare, other xanthomatous processes, and rheumatoid nodules.
In this case, a punch biopsy was necessary (the defect from which was closed carefully with interrupted sutures). Such procedures are discouraged in patients with larger and more advanced lesions, for fear of inducing a nonhealing wound. In fact, ulceration, usually from trauma, is the most feared complication of NL—and effective treatment is hard to come by.
This patient was treated with perilesional injection of triamcinolone suspension 10 mg per cc and given a prescription for 0.1% tacrolimus cream (to be applied twice daily). A follow-up visit was arranged for two months down the road. Her long-term prognosis is guarded, at best. Since she was already acutely aware of her risk for diabetes, there was no need for additional action in that arena.
Many other treatments have been tried for NL, with varying success, including dihydrochloroquine (Plaquenil and others) pentoxifylline, and TNF-a inhibitors.
TAKE-HOME LEARNING POINTS
• Early manifestations of necrobiosis lipoidica (NL) can be puzzling, and biopsy may be required for diagnosis.
• However, with advanced, obvious lesions, it is preferable to make the diagnosis of NL without biopsy, since punch biopsy can result in a nonhealing wound.
• Mature NL lesions become atrophic and yellowed, with marked telangiectasia formation on their surfaces.
• Just 0.3% of diabetic patients ever develop NL, but most affected persons have a family history of diabetes or an abnormal glucose tolerance test results, if not a personal history of diabetes.
