Basaloid tumors arising from seborrheic keratosis: Malignant basal cell carcinoma or benign basaloid follicular hamartomatous proliferation?

Abstract

Background: Basaloid tumors arising from seborrheic keratosis (SK) that resembled basal cell carcinoma (BCC) were infrequently observed in our patients. They also exhibited morphologic features similar to those of trichoblastoma or basaloid follicular hamartoma. Methods:We retrospectively collected cases of SK with basaloid tumors from 2001 to 2017. Ten cases of BCC, five of nevus sebaceus with trichoblastoma, five of trichoblastoma, and five of trichoepithelioma were included as controls. Tumorassociated antigens Bcl-2, CD10, PHLDA1, and CK20 were tested. Antigenic markers CD34 and CD10 were used to analyze peritumoral stroma features and Ki-67 and pHH3 to measure the mitotic activity.Results: Ten cases of SK with basaloid tumors were found and all located in non-sunexposed areas, including five men and five women, with a mean age of 61 years. A distinct PHLDA1 staining was not observed. The staining patterns of basaloid tumor lobules associated with SK were similar to the benign control group. Bcl-2 staining in the tumor lobules was mostly negative. Peritumoral CD10 stain and CK20-positive Merkel cells in the lobules were observed and the mitotic counts were low.Conclusion: Basaloid tumors arising from SK are not always BCC. They were all benign follicular hamartomatous proliferation in this case series. K E Y W O R D S basal cell carcinoma, basaloid tumor, follicular induction, immunohistochemistry, seborrheic keratosis

Immunohistochemical expression of p53, Ki67, α-SMA, CD44 and CD31 in different histological subtypes of basal cell carcinoma

“…Kramer et al also found no correlation between the proliferative index and the aggressive patterns of BCC [ 39 ]. Other studies reported that Ki67 expression was positive in all of the BCC subtypes but varied in intensity between recurrent BCCs and non-recurrent ones, with a higher expression of Ki67 in the recurrent cases [ 40 , 41 ]. Horlock et al observed that the morpheaform, infiltrating and superficial subtypes of BCC had the most intense Ki67 reactivity and highlighted the association between high levels of proliferation and BCC subtypes [ 42 ].…”

“…Other studies reported that Ki67 expression was positive in all of the BCC subtypes but varied in intensity between recurrent BCCs and non-recurrent ones, with a higher expression of Ki67 in the recurrent cases [40,41].…”

Seborrheic Keratosis With Malignant Transformation (Invasive or Noninvasive Squamous Cell Carcinoma Arising in Seborrheic Keratosis): A Clinicopathologic and Immunohistochemical Study of 11 Cases

“…Combined cases of seborrheic keratosis and basal cell carcinoma have also been reported in several articles. 12,15,16,28,[40][41][42][43][44][45][46][47][48][49] In such cases, the transition from seborrheic keratosis to basal cell carcinoma has not been clearly confirmed. Instead, nests of basal carcinoma are scattered throughout the seborrheic keratosis or collide with adjoining seborrheic keratosis.…”

Familial multiple basaloid follicular hamartoma

“…Although FMBFH generally presents at birth or in early childhood, milder variants may be recognized later in life [6,7]. Generalized forms of BFH are usually associated with systemic manifestations, which vary according to the subtype and can include cystic fibrosis, diffuse alopecia, and various autoimmune diseases (such as myasthenia gravis or systemic lupus erythematosus), [2,8,9]. Other systemic diseases, such as hypertension, diabetes mellitus, or breast cancer, have also been reported in these patients, although it is unclear if this association exceeds that found in the general population.…”

“…Vismodegib, an inhibitor of the hedgehog signaling pathway, might play a role in the treatment of severe disease in the future [12]. The prognosis is usually excellent, unless associated systemic disorders and/or BCC develop [8,9].…”