Introduction
Necrobiosis lipoidica (NL) is a rare granulomatous disorder characterized by well-circumscribed
yellowish plaques affecting the anterior shins, often in patients with diabetes. Clinical
examination is typically sufficient to make the diagnosis, but skin biopsy is sometimes
required. Here we present a patient who received a misdiagnosis of sarcoidosis that
was unsuccessfully treated who was found on re-examination and biopsy to have an atypical
papular presentation of NL.
Case report
A 52-year-old white woman presented for evaluation and treatment of reddish-brown
to orange-yellow firm papules on her anterior shins and lateral calves (Fig 1, A and
B). She carried a presumed diagnosis of sarcoidosis and was treated previously with
topical corticosteroids, intralesional corticosteroids, oral antibiotics, and oral
methotrexate over 5 years without improvement.
Fig 1
A case of NL in a 52-year-old woman. A and B, Clinical images of reddish-brown to
orange-yellow firm papules on anterior shins and lateral calves at presentation.
She recently was diagnosed with asthma, but otherwise denied any history of extracutaneous
organ involvement. Her previous evaluation included normal ophthalmologic examination,
chest radiograph, and pulmonary function testing. She reported a history of prediabetes
and had a family history of diabetes mellitus.
A skin biopsy found broad bands of necrobiotic collagen in the dermis, with admixed
lymphocytes, histiocytes, plasma cells, and multinucleated giant cells (Fig 2, A and
B). Re-examination of biopsies taken from 3 locations 5 years prior showed granulomatous
inflammation throughout the reticular dermis and areas of altered hypocellular collagen
with a layered appearance.
Fig 2
Histopathologic images from skin biopsy specimen before treatment. A, Broad bands
of necrobiotic collagen with a layered appearance. B, Granulomatous inflammation with
admixed lymphocytes, histiocytes, plasma cells, and multinucleated giant cells can
be seen at higher power. (Hematoxylin-eosin stain; original magnifications: A, ×40;
B, ×200.)
The patient's methotrexate was stopped, and pentoxifylline, hydroxychloroquine, and
topical clobetasol (0.05% ointment) was initiated. At a 6-month follow-up appointment,
a significant improvement in the appearance of the cutaneous lesions was noted, with
some residual reddish-brown papules.
Discussion
Necrobiosis lipoidica, first described by Oppenheim in 1929,
1
is a chronic granulomatous disorder. It is isolated to the lower legs in 85% of cases
but in 15% of cases may involve other locations such as the abdomen, upper extremities,
or scalp.
2
Approximately one-third of patients with NL have or eventually have diabetes mellitus.
3
It more commonly affects females, with a female/male ratio of 3 to 1.
1
Classic lesions are telangiectatic yellow-brown atrophic plaques. The lesions can
resolve spontaneously or can persist and ulcerate in 15% of cases.
4
The pathogenesis of NL is not fully understood; hence, there is no consensus on optimal
treatment. First-line treatment often consists of topical steroids, intralesional
steroids, or topical calcineurin inhibitors, although other commonly used therapies
include pentoxifylline, antimalarials, tumor necrosis factor inhibitors, phototherapy,
and mycophenolate mofetil, among numerous other options.
5
A diagnosis of NL can be confirmed via histopathology, particularly if the lesions
do not have the classic appearance. Biopsies of NL find layers of horizontal granulomatous
inflammation in the dermis, in an arrangement that is layer cake–like in appearance.
5
The granulomas are primarily composed of histiocytes and multinucleated giant cells,
whereas the intervening layers of inflammatory infiltrate are predominantly lymphocytic
with some plasma cells and eosinophils. The presence of plasma cells and an absence
of mucin help differentiate NL from granuloma annulare. The alternating areas of necrobiotic
collagen may help differentiate NL from sarcoidosis.
6
This case represents an atypical variant of NL in which it both presented and persisted
with a purely papular morphology, giving it a sarcoidlike clinical appearance. Previously
there were reported cases of sarcoid skin lesions with histology resembling NL,
7
but these cases exhibited symptoms of systemic sarcoidosis and presented with ulceration.
There also are reports of papules developing within—or in conjunction with—the classic
atrophic plaques of NL.
1
This case illustrates that dermatologists should consider this atypical variant of
NL when faced with papular lesions localized to the anterior shins without systemic
manifestations. If suspected, histopathologic confirmation should be sought, as early
diagnosis can impact both prognosis and optimal treatment.