Tests
Tests to consider
dermoscopy
Test
The diagnosis of seborrheic keratosis is generally made clinically, but dermoscopy is increasingly used in primary and secondary care to differentiate between benign and malignant pigmented lesions. The UK National Institute of Health and Care Excellence guidance recommends that any patient undergoing a specialist assessment for pigmented lesions must be examined with a dermatoscope.[24]
The characteristic dermoscopic features of seborrheic keratosis are milia-like cysts and comedo-like openings. Milia-like cysts are white or yellowish round structures that correspond to small intraepidermal, keratin-filled cysts (horn pearls). They are not exclusively found in seborrheic keratosis as they are also seen in congenital nevi and papillomatous dermal nevi but less frequently. Comedo-like openings (also called pseudofollicular openings or crypts) are brownish holes in the surface of seborrheic keratosis that correspond histologically to keratin-filled invaginations of the epidermis.[26][29][30]
Result
features of seborrheic keratosis
biopsy and histopathologic examination
Test
Biopsy is recommended in any isolated dark seborrheic keratosis, or where there is otherwise clinical suspicion for malignancy (e.g., lesions that itch or bleed, or become inflamed and red).[28] Sharply defined exophytic lesions growing intraepidermal proliferations composed of mature basaloid cells. The characteristic histologic features are keratin-filled invaginations and small cysts (horn cysts). Hyperkeratosis is present in variable degrees.
Result
features of seborrheic keratosis
reflectance confocal microscopy (RCM)
Test
RCM is a noninvasive imaging method that allows the in vivo examination of skin at cellular-level resolution. RCM features that indicate the diagnosis of seborrheic keratosis are: cerebriform surface structures; keratin-filled invaginations; corneal pseudocysts; a regular honeycomb pattern at epidermal layers; cords and polymorphous papillae at the dermo-epidermal junction; melanophages and looped vessels at the papillary dermis; and the absence of RCM features suggestive of malignancy.[27]
Result
features of seborrheic keratosis
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