Case Number : Case 751 - 2nd May Posted By: Guest

Folliculosebaceous cystic hamartoma.

Late stage of trichofolliculoma, so-called sebaceous trichofolliculoma.
A central cystic infundibulum with numerous sebaceous lobules radiating from it, all of them embedded in a fibromyxoid stroma.

Folliculosebaceous cystic hamartoma.

Sebaceous trichofolliculoma

The dense collagenous stroma with cleft like spaces, spinde cells and myxoid areas will make it FSCH and not only sebaceous trichofolliculoma.

In terms of clinical management, both entities are hamartomas, so does it make any difference in the real world?

PS. This lesion appears to communicate with the surface epithelium which is generally lacking in FSCH.

This looks like a flat endophytic instead of papillary/polypoid lesion, with vertical, deep penetration of a keratin filled infundibulocystic space that (as pointed out by Bansal) has surface communication. Rare follicular and predominantly radial sebaceous lobules. Focally dense stroma, lacking adipose tissue. The epidermis adjacent appears unremarkable.

I would favor a [color=#000080][i]sebaceous trichofolliculoma[/i][/color] over a f[color=#1C2837][font=arial, verdana, tahoma, sans-serif]olliculosebaceous cystic hamartoma[/font][/color], given the above features. The two have a lot of feature overlap[font=arial, verdana, tahoma, sans-serif][color=#1C2837] and differentiation is often difficult.[/color][/font]

I've just received my brand new "Cutaneous Adnexal Tumors", by Kazakov et al. I learned from a quick glance on its pages that late stage of trichofolliculoma, sebaceous differentiation in trichofolliculoma, sebaceous trichofolliculoma and folliculosebaceous cystic hamartoma are one and the same entity.
However, some recognize folliculosebaceous cystic hamartoma as a separated entity that differs from its look-alikes by adipose metaplasia in the stroma.

Interesting Dr Robeldo, I have got also my copy a week ago. Will definitly check these entities in it soon. It is an excellent book really....

Sebaceous trichofolliculoma vs. folliculosebaceous cystic hamartoma. The two are difficult to tell apart, and at least some think that it may be the same thing, as pointed out above. I went with sebaceous trichofolliculoma, and a colleague thought it was folliculosebaceous cystic hamartoma, just like the discussion above.

Sebaceous trichofolliculoma