Case Number : Case 4089 - 22 September 2022 Posted By: Saleem Taibjee

Trichilemmoma with reactive atypia vs SCC with trichilemmal differentiation. Favour former. 

Favor irritated/inflammed trichilemmoma.. 

Trichilemmoma. There seem to be some atypia, not sure if it is reactive change in irritated/ inflamed lesion or signify trichilemmal carcinoma in situ

Trichelemmoma with some reactive changes

Yes. Trichilemmoma with reactive changes. 

I can see that you are all in the same ballpark. I also reported the original histology (shave procedure) on this case which was very similar. I think it is noteworthy that this is a recurrent lesion. In my experience benign trichilemmomas virtually never recur. The additional immunohistochemistry was interesting in this case (see below). There is some tumour staining with CD34 which supports genuine trichemmal lineage. However, there is also marked upregulation of p53. Of course, p53 is not proof of dysplasia, but given the overall context is perhaps significant. Hence I feel that this could be a genuine 'low grade' trichilemmal carcinoma. The lobulated dermal profile would suggest minimal metastatic potential (in-situ versus 'pushing invasion'). However, as a precaution I have opted to follow up the patient for a couple of years as for SCC.

Yes Saleem This is a very great case. Trichilemmal carcinoma isn’t a ghost lesion, but a reality.