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Journal of the American Academy of Physician Assistants:
doi: 10.1097/01.JAA.0000433873.93906.19
Dermatology Digest

Large plaques in a patient with diabetes

Ma, Ben-Jiang PhD, MHS, PA-C; Mamish, Ziad MD; Hammond, Stacie MHS, PA-C

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Ben-Jiang Ma, Ziad Mamish, and Stacie Hammond practice endocrinology at Sacred Heart Hospital in Pensacola, Florida. The authors have indicated no relationships to disclose relating to the content of this article.

Joe R. Monroe, PA, MPAS, department editor

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CASE

A 35-year-old white woman was admitted to the hospital after an episode of diabetic ketoacidosis (DKA) that was treated per protocol. Physical examination revealed mild hirsutism and the presence of large plaques about t10 cm by 2 to 4 cm (3.9 by 0.8 to 1.6 inches) in size with irregular brownish borders and telangiectatic, somewhat atrophic centers on the bilateral pretibial surfaces (Figure 1). The lesions were not tender upon palpation. The patient said that the lesions developed several years before she was diagnosed with diabetes and have progressively enlarged.

Figure 1
Figure 1
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THE MOST LIKELY DIAGNOSIS IS

* Livedoid vasculopathy

* Cutaneous sarcoidosis

* Necrobiosis lipoidica

* Granuloma annulare

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DISCUSSION

The correct answer is necrobiosis lipoidica, previously called necrobiosis lipoidica diabeticorum and dermatitis atrophicans lipoidica diabeticorum, reflecting the prevalence of this condition among patients with diabetes. Due to the increased diagnosis of this condition in patients without diabetes, the current nomenclature excluded diabetes wording.

The cause of necrobiosis lipoidica is unclear. The lesion is histologically similar to microangiopathy as seen in diabetic retinopathy and nephropathy, with deposits of glycoprotein, immunoglobulins, and complement C3 in blood vessel walls. The presence of abnormal and defective collagen fibrils and increased cross-linking leads to the thickening of basement membrane. Inflammation may occur and result in antibody-mediated vasculitis and tumor necrosis factor (TNF)-induced granulomation. Cases of untreated lesions leading to squamous cell carcinoma have been reported.

The onset of necrobiosis lipoidica usually occurs in patients 30 years and older, but can occur in children, although rare. Women are 3 times more likely to be affected than men. Necrobiosis lipoidica is prevalent in about 0.3% of patients with diabetes and is more common in patients with type 1 diabetes. About 20% of patients had necrobiosis lipoidica onset before being diagnosed with diabetes, 25% of patients had coincidence, and most were diagnosed with diabetes before necrobiosis lipoidica occurred. The severity of necrobiosis lipoidica is not correlated to the degree of glycemic control.

Diagnosis Patients with necrobiosis lipoidica may be asymptomatic due to damage to cutaneous nerves (75% of cases) or may experience extreme pain if the nerves are still intact. Because necrobiosis lipoidica may be the first sign of diabetes, consider blood glucose screening. Necrobiosis lipoidica is diagnosed clinically and can be confirmed histologically with skin biopsy, although a biopsy usually is not required.

Classic necrobiosis lipoidica lesions begin with small papules or patches that coalesce over time to form large round or oval plaques with shiny, atrophic centers with or without indurated borders. Initial telangiectasia and granulomation give the lesions a red to brown color that becomes more yellow over time as collagen fibrils and fat are deposited. Isomorphic necrobiosis lipoidica lesions often occur bilaterally on multiple spots on the lower extremities, consistent with Koebner phenomenon. This phenomenon refers to linear distribution of skin lesions, sometimes bilaterally, although in the case of necrobiosis lipoidica, patients often deny a history of previous skin trauma.

Differential diagnoses The appearance of the lesion, presence of Koebner phenomenon, predominance of lower extremity distribution, and absence of pain in most cases, along with the pertinent patient history, are the clinical distinguishing features that point to necrobiosis lipoidica in this patient.

Livedoid vasculopathy is characterized by painful macular/papular or ulcerative skin lesions with smooth, pale, and atrophic centers and pigmented and telangiectic borders. A non-inflammatory vascular disease, livedoid vasculopathy is caused by focal thrombosis and endothelial dysfunction.

Cutaneous sarcoidosis is the skin manifestation of non-caseating granuloma. This “great imitator” of many skin conditions presents as patches, papules, ulcers, scars, and even ichthyosis and alopecia.

Granuloma annulare is a benign, asymptomatic, granulomatous skin lesion that usually results from small macules or papules to form annular erythematous patches. These lesions often are found on the hands and feet. The condition is usually self-limited and no treatment is needed.

Treatment Topical glucocorticoids are the first-line treatment for necrobiosis lipoidica. Glucocorticoids also can be given intralesionally and systemically. For more advanced lesions, tacrolimus ointment, tretinoin cream, and topical bovine collagen are alternatives.

TNF-alpha inhibitors, including etanercept, adalimumab, and infliximab, and thalidomide have been reported as effective. The antidiabetic thiazolidinedione drugs have been used with some success, and are believed to suppress TNF-alpha-mediated inflammation. The oral anti-thrombotic agents pentoxifylline and ticlopidine were reported effective. However, aspirin and dipyridamole have not proven consistently effective.

Physical therapies include protective stockings, ultraviolet A light therapy alone or with topical psoralen, photodynamic therapy, and pulse dye laser.

© 2013 American Academy of Physician Assistants.

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