Case Number : Case 1782 - 28 March - Dr Uma Sundram Posted By: Guest

Lots of information in these slides to lead you to the correct diagnosis... nice case from Dr Uma Sundram

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My impression is there are some follicles ( secondary ) radiating from a central dilated one ( primary ), and other smaller budding follicles ( tertiary ) radiating from the secondary ones. This specialised epithelial growth is surrounded by an equally specialised stroma. There is also some occasional and questionable inner root sheath differentiation, in fig 3/4, and some outer root sheath differentiation in fig 2 top left, but no convincing pilomatrical differentiation to indicate a panfolliculoma. If I'm correct, this is a trichofolliculoma. Clinical findings fit well.

I agree with trichfolliculoms

I also thought of trichofolliculoma but history of multiple lesions looks weird as these lesions are usually solitary. Articles are extremely scarce here the most recent one. I also thought of multiple familial trichoepithelioma but the histology seems consistent with trichofolliculoma. Nice case

A rare clinical presentation of multiple trichofolliculomas (thank you, Raul, for referring that case report). Whereas trichofolliculoma undergoes the typical changes of the hair growth cycle, this case shows features of a late-stage trichofolliculoma, to wit, single cell apoptosis and thickening of the epithelial lining of the central cyst-like infundibulum, reminiscent of outer root sheath epithelium in a normal hair follicle in catagen.

Agree with trichofolliculoma, unusual clinical variant of multiple lesions... 

Seems like a trichofolliculoma

Should we not see complete differentiation of the hair follicles including vellus hair shafts, inner root sheath, bulbs and papillary mesenchymal cells in trichofolliculoma. I'm leaning more towards basaloid follicular hamartoma (centred on pre-existing follicles, lack papillary mesenchymal cells, can closely resemble mini-BCC, can present as multiple papules).

Difficult case. Initially, I did think about a trichofolliculoma. Agree with Richard's points , lack of PMCs etc, favouring BFH.

Yes, agree with Richard. This must be a basalod follicular hamartoma!

My opinion is basaloid follicular hamartoma. History suggests possibility of basaloid follicular hamartoma syndrome. Needs sampling of some additional papules for comparison and further familial investigation.

Familial Basaloid Follicular Hamartoma: Lesional Characterization and Review of the Literature

American Journal of Dermatopathology . 25(2):130-137, April 2003.

Felt I need to to challenge my own suggestion! We should also consider multiple infundibulocystic BCC in this case.  It might actually be a better as BFH are usually smaller lesions than this one.

R

The last Richard's suggestion is more convincing to me.  But the few ICBCCs I saw showed much pigment and didn't contain any specialized stroma. I'm not sure but seems to see some papillary mesenchimal body in fig 4 right half...

To my eye that is a pseudo-PMC created by the palisading cells demarcating from central cells. Check out the adjacent lobules which show the same feature. Trichoepitheliomas almost always have 50% stroma to 50% epithelium (large nodular TB's excepted).  I strongly favour IFCBCC now - not sure why the penny did not drop earlier!  CK20 can be quite useful as in my experience they are preserved in BFH compared with rarity in IFCBCC.

I agree for basaloid follicular hamartoma as a differential but I would not like to call this a BCC. 

Just to add another diagnostic hypothesis, a badly oriented sectioning of a pilar sheath acanthoma may have prevented the clear visualization of its typical cystic invagination, but again the multiplicity of lesions is a very odd clinical presentation.

When I first saw the images above, I did consider infundibulocystic basal cell carcinoma, but the dense stroma and the catagen changes made me favor trichofolliculoma.

CPC is sometimes a difficult practice: who should win: clinic or pathology?

I think this case is histologically a trichofolliculoma, but clinic doesn't fit well.  So we are looking for an alternative clinically reasonable diagnosis, and maybe this is the right way. But I want still favour TF, multiple variant.  

Hi everyone, my apologies for the late post. This is a great discussion with many interesting points. We were between infundibulocystic BCC and trichofolliculoma as well. Three lesions were biopsied and all three looked identical. We asked the clinician to work with the patient on a potential familial situation, either of multiple infundibulocystic BCC (several recent papers on this), familial TF, or familial basaloid follicular hamartoma syndrome. Staining was not particularly helpful (numerous CK20+ Merkel cells in lesion) as CK20+ has been reported in IFCBCC.

A good old p53 could be useful in this kind of situation. And I think Richard would agree with me on that :)