Other Tests
Since several reports have associated hyperkeratosis lenticularis perstans (Flegel disease) with an endocrinopathy, obtain a thorough and complete systems review, as well as social and family histories. Laboratory, radiographic, or surgical tests are not needed, unless indicated by information gleaned from these sources.
Procedures
Skin biopsy with hematoxylin and eosin staining shows characteristic findings of hyperkeratosis lenticularis perstans (Flegel disease). Electron microscopy is not essential.
Histologic Findings
A discrete area of hyperkeratosis occurs (with areas of parakeratosis) overlying a thinned stratum malpighii and thinned-to-absent granular layer. Irregular acanthosis and some vascular dilatation are peripheral. A lymphoid infiltrate with occasional histiocytes in a bandlike pattern in the papillary dermis typically is seen. [12] See the images below.
Hematoxylin and eosin-stained section, low magnification. Epidermal hyperplasia with rete elongation surmounted by a thickened, compact, hyperkeratotic scale. A bandlike lymphoid infiltrate expands the papillary dermis.
Hematoxylin and eosin-stained section, medium magnification. The lateral edge of the lesion demonstrates abrupt hyperkeratosis and a combination of epidermal atrophy and acanthosis.
Hematoxylin and eosin-stained section, high magnification. The section shows mostly orthokeratotic scale, thinning of the epidermis with a diminished granular cell layer, and an infiltrate of lymphocytes in the superficial dermis, which approximate the dermal-epidermal interface.
Some evidence has indicated that older lesions may show some histologic differences compared with newer ones. [13] Older lesions can show absence of epidermal atrophy and may infiltrate the upper dermis. Ultrastructural studies also reveal the presence of many normal-appearing, membrane-coating granules in the keratinocytes of an old lesion, whereas these normal organelles were not found in the keratinocytes of earlier hyperkeratotic skin lesions. [14]
Electron microscopy
Several authors have reported an absence or decrease in the number of membrane-coating granules, or Odland bodies, within lesional keratinocytes. Although other authors have found Odland bodies to be present, most suggest that the membrane-coating granules may undergo some alterations in number or morphology. Perilesional skin uniformly shows normal keratinocyte differentiation.
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Clinical photograph of the upper thigh showing numerous red-brown papules with sparing of the inguinal crease.
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A higher-powered view of the patient seen in the previous image. Photograph of the upper thigh demonstrates 1- to 4-mm, noncoalescing keratotic papules.
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Hematoxylin and eosin-stained section, low magnification. Epidermal hyperplasia with rete elongation surmounted by a thickened, compact, hyperkeratotic scale. A bandlike lymphoid infiltrate expands the papillary dermis.
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Hematoxylin and eosin-stained section, medium magnification. The lateral edge of the lesion demonstrates abrupt hyperkeratosis and a combination of epidermal atrophy and acanthosis.
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Hematoxylin and eosin-stained section, high magnification. The section shows mostly orthokeratotic scale, thinning of the epidermis with a diminished granular cell layer, and an infiltrate of lymphocytes in the superficial dermis, which approximate the dermal-epidermal interface.
