Case Number : Case 1047 - 27th June Posted By: Guest

[size=4][color=#000000][color=#000000][color=#000000]Trichoblastoma.[/color] [/color][/color][/size]

[i][color=#000000][size=3][size=3][color=#000000][size=4]Dr Carr. Are there differences between the immunohistochemistry of small and large nodular trichoblastoma, trichoepithelioma (cribriform trichoblastoma) and desmoplastic trichoepithelioma? I tried looking into the literature once, but was discouraged by contradictory findings and differences in lumping and splitting. Your opinion would be appreciated. Thank you. [/size][/color][/size][/size][/color][/i]

[i][color=#000000][size=3][size=3][color=#000000] [/color][/size][/size][/color][/i]

Agree.

[img]https://dermpathpro.com/uploads/spot_diagnosis_comment_img/CASE1047_RAC6826x5_CD10_Label.jpg[/img]

[img]https://dermpathpro.com/uploads/spot_diagnosis_comment_img/CASE1047_RAC6826x10b_CD10_Label.jpg[/img]

Yes there are differences. DTE don't have papillary mesenchymal cells and the typical stromal pattern of CD10 that is seen in TB/TE (tight hugging of tumour epithelium). DTE almost always have Merkel cells (4 to 5 or more per x20 field) whereas TB/TE have >5 Merkel cells (in the whole tumour) in only around 30% of lesions (also seen in ~5% of nodular and TE-like BCC). Can you e-mail [email="richard.carr@swft.nhs.uk"]richard.carr@swft.nhs.uk[/email] and I will give you (or any other colleague) access to our review papers and talks (including my obsession with KA and follicular SCC). The review on basaloid tumours does have an error of a DTE with intra-tumoural perineural invasion I wrongly favoured as a BCC!! We live and learn!!

By the way this case is not resolved.

There are two patterns of CD10 expression, the first one is typical of TB/TE spectrum and the second one is typical of BCC. So I am considering this as a BCC developing within an old standing trichoblastoma (small lobular trichoepithelioma like trichoblastoma).

Collision of trichoblastoma (left), evidenced by the specific follicular stroma which can be shelled out from the surrounding dermal stroma, and basal cell carcinoma (right), illustrated by relatively scarce non-cellular stroma with increased mucin that imparts an adenoid arrangement to the epithelial component. Also, CD10 staining highlights areas showing stromal expression, typically of trichoblastoma, and epithelial expression, typically of basal cell carcinoma.

Agree with trichoblastoma with nodular basal cell carcinoma.

Yes this was a case of trichoblastoma and BCC confirmed with CD10 as discussed by colleagues.
Thanks and enjoy your weekends.

Nice case! In the context of the history, the asymmetric distribution of the tumor, with increased mitotic rate, larger nests, and decreased stromal cellularity suggested BCC arising in a long-standing trichoblastoma.