Case Number : Case 372 Posted By: Guest

Phillip McKee - Overseas Consultations (Cave Creek, Arizona, USA) Wrote:

There waa focal epidermal connection not shown in these images. One has to be very careful with "ductal differentiation". It should be proven by immunohistochemistry. In any event, tumors arising from the follicular unit can show ductal differentiation (of apocrine derivation). I agree with Richard that this lesion is a trichilemmal carcinoma. Have a great weekend.

Submitted on 11/11/2011 13:10
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Sasi Attili - (UK) Wrote:

Thanks a lot Dr. Mona. I was put off by that. Looks like Malignant proliferating pilar tumour it is...

Submitted on 11/11/2011 11:45
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Mona Abdel Halim - Dermatology Dept, Cairo Univ. (Egypt) Wrote:

Dear Dr Sasi: apocrine and sebaceous duct differentiation can be seen sometimes in trichilemmal cysts (Weedon's skin pathology). So it is accepted,,

Submitted on 11/11/2011 11:02
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Sasi Attili - (UK) Wrote:

Is that not a duct in the 4th pic (to the lower right in the pic)?

Submitted on 11/11/2011 10:40
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Mona Abdel Halim - Dermatology Dept. Cairo Univ. (Egypt) Wrote:

After some reading, I think this is malignant proliferating pilar tumor.

Submitted on 11/11/2011 10:34
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Richard Carr - Warwick (UK) Wrote:

I think we do have cellular atypia so I would call it a low-grade (well differentiated) follicular carcinoma. If not connected directly with the surface a malignant proliferating pilar tumour. If connected with the follicular units/surface in another plane of section a follicular (tricholemmal) squamous cell carcinoma. I favour this is pseudoglandular/acantholytic differentiation but it can be very difficult on occasions as squamoid ductal differentiation and squamous morules are not exclusive to folliclar tumours (I have seen them in hidradenoma, hidradenocarcinoma and even adenoid cystic carcinoma). BCC is less likely as we don't have good palisading or mucin in the retraction space.

Submitted on 11/11/2011 06:39
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Sasi Attili - (UK) Wrote:

Clear cell tumour. Solid and cystic pattern with cysts of various sizes. Numerous squaqous eddies. No epidermal connection obvious. The varying cysts sizes and the three abnormal mitoses in the last field make me thing this is malignant rather than benign. Differentials include Clear cell SCC, trichilemmal Carcinoma, Sebaceous carcinoma and Clear cell Hidradenocarcinoma. I can see one ductal structure in the last pic and hence would go for Clear Cell Hidradenocarcinoma as squamous metaplasia has been described. Moreover I would expect an epidermal connection is the first two and the cells do not look sebaceous to me. Regardless I would probably like to see PAS, CEA and EMA to confirm glycogen and ductal structures. However the atypia I am not sure is enough to call this a carcinoma or simply a 'atypical clear cell hidradenoma'. I would go for carcinoma

Submitted on 11/11/2011 06:35
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Mona Abdel Halim - Dermatology Department, Cairo University (Egypt) Wrote:

This is a very difficult and challenging case. My first idea is a follicular SCC with clear cell change and extensive necrosis (transversly cut), My second DDx is a trichilemmal carcinoma, again transversly cut (however, I could not identify an esinophilic BM and the peripheral palisading is not that evident). My final suggestion is a variant of keratotic BCC (BCC with squamous differentiation and central keratinization) with extensive squamous morule formation and trichilemal keratinization..

Submitted on 11/11/2011 06:04
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I. Abdul-kadir - SJUH (Leeds, UK) Wrote:

I was thinking a proliferating trichilemmal cyst, until the last picture (ductal differentiation). Now I'm thinking a hidradenocarcinoma. I don't think it's benign.

Submitted on 11/11/2011 05:58
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Peter Karolyi - () Wrote:

I think it is a hair follicle derived tumor with features os trichilemmoma, pilomatrixoma and focally ductal structures (from sebaceous glands?). I consider it benign but the edge (infiltration?) is important but can not be seen in the pictures.

Submitted on 11/11/2011 05:49
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