Diagnostic Considerations
Consider disseminated superficial actinic porokeratosis (DSAP). Porokeratoses are progressive, hyperkeratotic, irregular plaques with a characteristic and prominent peripheral keratotic ridge. The superficial disseminated form occurs as a generalized symmetric process confined exclusively to sun-exposed areas. Lesions are small, 1- to 3-mm, keratotic lesions, with a central dell and a peripheral keratotic ridge that may number in the hundreds. DSAP is a relatively common condition occurring in the third and fourth decades, and it slowly progresses over years. Histologically, the peripheral, raised, keratotic ridge translates into a hyperkeratotic invagination in the epidermis termed cornoid lamellae. Cornoid lamellae are abrupt well-defined stacks of parakeratin confined to the periphery of the lesion. The underlying epidermis lacks a granular layer and frequently shows dyskeratosis.
Numerous reports exist in the literature that associate hyperkeratosis lenticularis perstans (Flegel disease) with an endocrinopathy. At a minimum, 4 reports were associated with adult-onset diabetes and 2 with hyperthyroidism.
A relationship between hyperkeratosis lenticularis perstans (Flegel disease) and malignancies has been suggested. One report describes epithelial tumors (basal and squamous cell carcinomas) occurring at distant, uninvolved, and nonlesional sites in patients with a familial hyperkeratosis lenticularis perstans (Flegel disease) lineage. A possible association between cancers of the digestive system and hyperkeratosis lenticularis perstans (Flegel disease) also has been implied.
The association of hyperkeratosis lenticularis perstans (Flegel disease) with endocrinopathies, skin, and GI neoplasms is weak at best. Certain factors (including rarity of hyperkeratosis lenticularis perstans (Flegel disease) and high prevalence of associated diseases) suggest a reporting bias.
Differential Diagnoses
-
Clinical photograph of the upper thigh showing numerous red-brown papules with sparing of the inguinal crease.
-
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.
-
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.
