Case Number : Case 824 - 14th August Posted By: Dr. Hafeez Diwan

Trichilemmoma

I think this is confluent and reticulated papillomatosis of Gougerot and Carteaud due to the presence of downgrowths of the epidermis from the bases between papillomatous areas. Age, gender and site also lend support to the hypothesis.

The skin sample looks like a shave. It is probably an Epidermal nevus.

[color=#1C2837][font=arial, verdana, tahoma, sans-serif][size=4]Epidermal nevus[/size][/font][/color]

[color=#1C2837][font=arial, verdana, tahoma, sans-serif]Epidermal nevus/acanthosis nigrican.[/font][/color]

Epidermal naevus

Epidermal nevus

I think this is an epidermal nevus.
A superficially/partially represented nevus sebaceus is my second thought.

There is often abnormal, superficial sebaceous or folliculosebaceous adnexa in addition to epidermal nevus changes for NS, but such a clue might be absent, in a small superficial shave. My suspicion for a nevus sebaceus is increased for any head/neck biopsies from an early adolescent (as in this case, 11 year old female), since NS tend to suddenly grow and become an item of patient concern, prompting a visit.

Histology shows seborrheic keratosis-like hyperkeratosis and reticulated acanthosis with blunt papillomatosis. It lacks significant basal hyperpigmentation, dermal adnexa, or keratin cysts.

In Figure 3 I see epithelial lobules with rounded contours, peripheral cells arranged in palisades and epitelial basement membrane easily seen, at least in some areas. The queratinocytes forming the lobules are realatively small and clear. I think these findings are suggestive of a trichilemmoma. By the other side the acanthosis and papillomatosis seen at the suprajacent epidermis are much more prominent and horizontally arranged than that seen at the superficial part of trichilemmomas. Maybe the explanation would be a trichilemmoma arising in a nevus sebaceous of Jadassohn.

[quote name='Romualdo' timestamp='1376498255']
In Figure 3 I see epithelial lobules with rounded contours, peripheral cells arranged in palisades and epitelial basement membrane easily seen, at least in some areas. The queratinocytes forming the lobules are realatively small and clear. I think these findings are suggestive of a trichilemmoma. By the other side the acanthosis and papillomatosis seen at the suprajacent epidermis are much more prominent and horizontally arranged than that seen at the superficial part of trichilemmomas. Maybe the explanation would be a trichilemmoma arising in a nevus sebaceous of Jadassohn.
[/quote]
I agree. Nevus sebaceous with trichilemmal and epidermal nevus features, but lacking sebaceous lobules, would make sense.

Acanthosis nigricans. The clinical impression was acanthosis nigricans.