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Granuloma annulare is a common benign inflammatory disorder of
uncertain pathogenesis that is classically characterized by asymptomatic,
flesh-colored to pink or violaceous, nonscaly annular plaques typically
located over the dorsa of the hands and feet. (Fig.
359-1) Less common variants include generalized,
perforating, and subcutaneous granuloma annulare. The lesions of
classic granuloma annulare are round to oval and are often misdiagnosed
as tinea corporis (eFig. 359.1). However,
unlike tinea infections, the lesions have a smooth, sometimes firm
border that lack epidermal scale. Lesions of subcutaneous granuloma
annulare appear as asymptomatic to slightly tender, flesh-colored
nodules that can occur anywhere, although they are often on the
lower legs and scalp. Atypical locations, including the palmar surfaces
and eyelids, have reported (eFig. 359.2).1 The
differential diagnosis of granuloma annulare includes tinea corporis,
necrobiosis lipoidica, rheumatoid nodules, and cutaneous sarcoidosis.
Adults who develop this disorder may be more likely to have diabetes,
but this association is not seen in children. Histologically, granuloma
annulare displays altered collagen and mucin surrounded by distinctive “palisade” of
histiocytes. There are also interstitial variants where the collagen
alteration is less obvious. In subcutaneous granuloma annulare,
the inflammatory process primarily involves the fat. Treatment is
generally unsatisfactory. Topical steroids or intralesional steroids
can limit progression, but results are not dramatic. Systemic steroids, isotretinoin,
hydroxychloroquine, dapsone, and ultraviolet light therapy have
been attempted in patients with disseminated granuloma annulare
with limited success. Fortunately, granuloma annulare is an indolent
process that eventually stabilizes and resolves without scarring
over several years.
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Necrobiosis lipoidica diabeticorum (NLD) is an uncommon inflammatory
dermatosis characterized by well-demarcated, yellowish-pink, shiny, atrophic
plaques often with prominent central telangiectasia. It is typically,
but not exclusively,
seen in diabetic patients. Only 0.3% of diabetics develop
NLD and its occurrence is independent of glycemic control. Although
it is more common in adult females, children with type I and type
II diabetes rarely develop NLD. It has been suggested that the presence
of NLD may signify an increased risk for nephropathy and retinopathy.2 Despite
its relationship to diabetes, the pathogenesis of NLD is uncertain.
Lesions most commonly occur on the pretibial region; however, the
upper extremities, trunk, and face can be affected. Lesions are
typically asymptomatic but can develop ulcerations in response to
trauma. Diagnostic evaluation should include a workup for diabetes. Histologically, NLD
is characterized by layers of degenerated collagen alternating with
granulomatous inflammation in the dermis and subcutaneous tissue.
Blood vessel walls ...