Dermatology Online Journal

A case of perforating necrobiosis lipoidica in an African American female
Farah R Abdulla MD, Pranav B Sheth MD
Dermatology Online Journal 14 (7): 10

Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio

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Abstract

An African American female with type II diabetes of 4 years duration presents with a 3-year history of smooth firm, dark brown plaques focally studded with comedone-like papules. Clinically and histologically her lesions were consistent with the rare entity perforating necrobiosis lipoidica.

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Case report

A 59-year-old African American female presented with a 3-year history of 5 asymptomatic, slowly enlarging lesions on both lower extremities. There was no history of trauma to these areas. Past medical history was significant for diabetes mellitus diagnosed 1 year prior to the onset of the lesions. The patient is otherwise healthy. Medications included Lantus and Novolog insulin. On full skin examination, involving the thighs and knees were 2-4 cm dark brown, smooth, firm centrally depressed plaques focally studded with hyperkeratotic papules (Figs. 1 & 2).

Figure 1	Figure 2
Figure 1. Several smooth, brown, centrally atrophic plaques Figure 2. Comedone-like plugs within dermal plaques

Microscopic examination of the lesions revealed a normal epidermis. Within the mid and deep reticular dermis were tiered layers of dermal collagen necrosis and fibrosis with a surrounding peripheral sparse lymphohistiocytic infiltrate (Fig 3). Dividing the epidermis, papillary dermis, and superficial reticular dermis was transepithelial elimination of basophilic necrotic material (Fig. 4). The clinical and histologic diagnosis was perforating necrobiosis lipoidica.

Topical steroids were unhelpful in improving these lesions. Our patient was subsequently treated with intralesional kenalog of 7.5mg/cc on 2 occasions resulting in decreased thickness and diameter of the lesions. She was lost to follow-up.

Figure 3	Figure 4
Figure 3. Tiers of necrobiotic collagen alternating with fibrosis Figure 4. Transepithelial elimination of necrotic connective tissue

Discussion

Necrobiosis lipoidica is a rare disorder found on the lower extremities. The dermatosis frequently is associated with diabetes mellitus. However, it is unrelated to the glucose control. It has a prevalence of 0.3 percent of the diabetic adult population [1]. Clinically, these lesions present as smooth yellow to dark brown plaques that most commonly occur on the lower extremities, but can develop anywhere. Atrophy with telangiectasia and ulceration are not uncommon. Histologically, they consist of tiers of necrobiotic collagen with fibrosis in the mid and deep reticular dermis with a lymphohistiocytic infiltrate. The epidermis may be atrophic or unchanged depending on the stage of the lesion.

Transepidermal elimination of foreign material is a feature characterizing the perforating disorders. For purposes of categorization, they are divided into "primary" and "secondary" perforating disorders. The primary perforating disorders reactive perforating collagenosis, elastosis perforans serpiginosa, acquired perforating disorder, and Kyrle disease are characterized by the transepidermal elimination of collagen, elastin, or necrotic connective tissue. The secondary perforating disorders are those disease entities in which the transepidermal elimination is incidental in another disorder. Our case of perforating necrobiosis lipoidica, as well as others such as perforating granuloma annulare and perforating sarcoidosis, are entities in this latter category.

Perforating disorders have considerable clinical variability. While the lesions of a primary perforating disorder appear as hyperkeratotic, centrally "excoriated" papules, secondary perforating disorders usually are dermal diseases consisting of smooth plaques or nodules that exhibit the unexpected finding of what appears to be keratotic papules or plugs. The latter corresponds histologically to the transepidermal elimination of connective tissue.

Transepidermal elimination in necrobiosis lipoidica was first noted in 1977 by Parra [2]. Specifically, the 3 reported cases were of transfollicular elimination of degenerated collagen presenting clinically as hyperkeratotic papules on the surface of the plaques. Since then, reported cases have included both transfollicular and transepidermal elimination of degenerated collagen, elastic fibers, and necrotic connective tissue. This is a rare phenomenon with few described cases in the literature [2, 3, 4, 5]. Consistent with the initial report, all subsequent cases show perforation histologically corresponding to the comedone-like plugs seen clinically.

The differential diagnosis in this particular case includes dermal granulomatous diseases such as granuloma annulare and sarcoidosis. Histology assists in differentiating these entities. The former is characterized by dermal collections of histiocytes, lymphocytes, and fibroblasts radially arranged around a focus of degenerated collagen fibers with central mucin deposition; the latter consists of naked granulomas located in the dermis.

Perforating necrobiosis lipoidica should be considered in the differential diagnosis of smooth dermal plaques containing what may look like hyperkeratotic papules or comedonal plugs. The disorder is benign and ulceration has been described within lesions of necrobiosis lipoidica that have perforation as a characteristic change. Treatment options include observation and topical or intralesional corticosteroids.

References

1. Muller SA, Winkelmann RK. Necrobiosis lipoidica diabeticorum. Arch Dermatol. 1966 Mar; 93(3): 272-81. PubMed

2. Parra CA. Transepithelial elimination in necrobiosis lipoidica. Br J Dermatol. 1977; 96: 83-6. PubMed

3. Torre C, Losada A, Cruces MJ. Necrobiosis Lipoidica: A Case with Prominent Cholesterol Clefting and Transepithelial Elimination. Am J Dermatol.1999; 21(6) 575-7. PubMed

4. Pestoni C et al. Two Girls with Necrobiosis Lipoidica and Type I Diabetes Mellitus with Transfollicular Elimination in One Girl. Pedia Dermatol. 2003; 20(3) 211-14. PubMed

5. McDonald L, Zanolli MD, Boyd AS. Perforating elastosis in necrobiosis lipoidica diabeticorum. Cutis 1996; 57(5) 336-8. PubMed

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