Reticulated acanthoma with sebaceous differentiation.

Clinical presentation

A 74-year-old man presented with an oval, well-demarcated patch (50 mm × 35 mm) on his abdomen that had been present for 10 months, characterized by marked asymmetry and variegated pigment, including reddish-yellowish color with peripheral hyperpigmentation (Fig 1, A).

Fig 1

A, Clinical presentation of the lesion showing its asymmetrical shape and variegated pigmentation. B, Dermatoscopic features, such as brownish pigmented reticular lines at the periphery, well-demarcated yellow structure, white reticular lines, and atypical vessels.

Dermoscopic appearance

Dermoscopy revealed dark yellowish-purplish pigmentation with brownish pigmented reticular peripheral lines, well-defined yellow structure, white reticular lines, and atypical vessels (Fig 1, A and B).

Histologic diagnosis

Histopathologic examination showed epidermal acanthosis, proliferation of basaloid and squamoid cells, and clusters of sebocytes in a reticulated seborrheic keratosis–like pattern. A diagnosis of reticulated acanthoma with sebaceous differentiation was made (Fig 2, A-C).

Fig 2

A-C, Histologic features of the lesion with progressive enlargement (Original magnifications: A, ×5; B, ×10; C, ×20) showing epidermal acanthosis and clusters of sebocytes in a reticulated seborrheic keratosis-like pattern.

Key message

Reticulated acanthoma with sebaceous differentiation is a rare, benign, cutaneous neoplasm, usually manifested on the trunk and rarely on the face or scalp of elderly patients, histologically characterized by sebocytes arranged in a band-like pattern, melanosis, and proliferation of basaloid and squamoid cells.

The multicomponent pattern with white linear structure (papillary dermal fibrosis), yellowish pigmented areas (clustered sebocytes mostly located at the bottom of tumor lobules), and peripheral reticular hyperpigmentation (basaloid and squamoid cells with melanin pigment) are the most distinctive dermoscopic findings leading to the diagnosis. The differential diagnosis includes malignant melanoma, basal cell carcinoma, Bowen disease, and eccrine poroma, all of which usually lack the yellow component related to sebaceous differentiation. Familiarity with its dermoscopic features is crucial to provide a noninvasive diagnosis of a underrecognized lesion, thus limiting surgical intervention.

Conflicts of interest

None disclosed.