Superficial epithelioma with sebaceous differentiation: immunohistochemical study of keratinocyte differentiation markers

ARTICLE

ejd.2011.1536

Auteur(s) : Yasuhiro Kawachi kyasuhir@md.tsukuba.ac.jp, Yasuhiro Fujisawa, Junichi Furuta, Yasuhiro Nakamura, Yoshiyuki Ishii, Fujio Otsuka

Department of Dermatology, University of Tsukuba, 1-1-1, Tennodai, Tsukuba 305-8575, Japan

Superficial epithelioma with sebaceous differentiation (SESD) is a rare benign tumor histologically characterized by superficial plate-like proliferation of basaloid cells with clusters and lobules of sebocytes. Here, we report a case of SESD and discuss the pathogenesis of the tumor, based on immunohistochemical staining for keratinocyte differentiation markers.

A 27-year-old man presented with a slightly pruritic erythematous lesion on the skin of the right chest that had been present for at least 10 years. There was no family history of similar skin lesions and no notable past history. Physical examination showed a 12 × 7 mm sized, erythematous, flat-topped, and slightly hyperkeratotic, well-demarcated plaque with brownish pigmented spots (figure 1A). With a clinical diagnosis of seborrheic keratosis, the tumor was completely excised and there has been no recurrence to date. Histopathological examination of the lesion revealed a superficial multilobular plate-like proliferation of basaloid cells (figure 1B) with multiple scattered nests of mature sebocytes (figure 1C). Foci of ductal differentiation were observed within the tumor mass (figure 1D) with lymphoid cell infiltration in the upper dermis. A diagnosis of SESD was made, based on these clinical and histopathological characteristics. Immunohistochemical analysis was performed for the following epidermal differentiation markers: keratin 14 (K14; marker for undifferentiated basal keratinocytes), keratin 10 (K10; marker for early-stage differentiated suprabasal keratinocytes), involucrin (marker for late-stage differentiated, upper spinous layer keratinocytes), filaggrin (marker for terminal differentiated, granular layer keratinocytes), keratin 7 (marker for secretory gland epithelia and ducts). The tumor showed homogeneous staining for K14 (figure 1E). There was no staining for K10 (figure 1F), involucrin (figure 1G), or filaggrin in the basaloid tumor cells. Positive staining for these markers was observed only in the upper squamoid non-tumor cells. The secretory gland epithelium markers K7 (figure 1H) and epithelial membrane antigen (figure 1I) were detected exclusively in nests of sebocytes and ducts.

SESD, which also has been referred to as reticulated acanthoma with sebaceous differentiation [1] and acanthomatous superficial sebaceous hamartoma [2], is a histologically distinct benign neoplasm characterized by a superficial plate-like proliferation of basaloid cells with foci of sebaceous differentiation [2-4]. The additional histological features of SESD include a verruciform structure, pigmentation of the basal layer and lymphoid cell infiltration in the upper dermis. Differential diagnoses from other cutaneous neoplasms with sebaceous differentiation include sebaceoma, sebaceous adenoma, trichoblastoma with sebaceous differentiation, apocrine poroma with sebaceous differentiation and basal cell carcinoma with sebaceous differentiation. However, SESD can be easily differentiated from these other neoplasms histologically by the superficial plate-like proliferation of monotonous small basaloid cells, which is also a histological characteristic of seborrheic keratosis.

The pathogenesis of sebaceous differentiation in SESD is not yet known. Therefore, we examined the expression of keratinocyte differentiation marker molecules in SESD to evaluate the differentiation stage of SESD. The observed staining pattern suggested that the tumor cells do not differentiate towards interfollicular epidermis but rather towards sebofollicular epithelium. This may explain why the overall plate-like configuration and the histological features of basaloid cell proliferation are similar to those seen in seborrheic keratosis, which is a tumor derived from the follicular infundibulum [3].

Disclosure

Financial support: none. Conflicts of interest: none.

References

1. Haake DL, Minni JP, Nowak M, Abenoza P, Nousari C.H. Reticulated acanthoma with sebaceous differentiation. Lack of association with Muir-Torre syndrome. Am J Dermatopathol 2009 ; 31 : 391-392.

2. Leboeuf NR, Mahalingam M. Acanthomatous superficial sebaceous hamartoma? A study of six cases with clarification of the nomenclature. J Cutan Pathol 2007 ; 34 : 865-870.

3. Akasaka T, Imamura Y, Tomichi N, Kon S. A case of superficial epithelioma with sebaceous differentiation. J Dermatol 1994 ; 21 : 264-267.

4. Kato N, Ueno H. Superficial epithelioma with sebaceous differentiation. J Dermatol 1992 ; 19 : 190-194.