Case Number : Case 1747 - 7 February - Dr Uma Sundram Posted By: Guest

Dr Uma Sundram has an intriguing Spot Diagnosis Case for you today, enjoy

Geoff Cross - DermpathPRO Projects

Deep desmoplastic dermal reaction, pallor of the epithelium, and attempts of keratin pearls within the downward epithelial ramifications, make me think of Verrucous/(Cuniculatum)Carcinoma

But I know this is a tricky and  controversial diagnosis...

?scc arising in hypertrophic lichen planus

I liked the above mentioned hypothesis of SCC arising in LP

Regressing keratoacanthoma. Neoplastic nests are embedded in a chronic inflamed and fibrotic stroma and they are composed by squamous cells whose nuclei are bland and whose cytoplasm become larger and more eosinophilic toward the center of the nests.

As Robledo, I also thought of regressing KA

Agree more on regressing KA

Agree with SCC in hypertrophic lichenplanus 

I cant see any atypia. I think more of a resolving (regressing) keratoacanthoma

I cannot decide based only on these images between regressing ka vs hypertrophic lichen planus. I do not think there is cancer here though. Favour regressing ka

Regressing squamoproliferative lesion, most suggestive of a regressing keratoacanthoma. Not convinced that this is invasive SCC.

I'm considering hypertrophic LP +/- KA/ well diff SCC

I don't think the lesion looks like it's regressing, but there is definitely lichenoid lymphocytic inflammation. Given the patients age and lack of atypia, I'm not sure I want to call this SCC. Tough.

I tried to photograph the fact that the lesion was a cystic one, and hence the diagnosis is proliferating epidermoid cyst, with consideration for an invasive squamous cell carcinoma arising in a proliferating epidermoid cyst. I agree with many of you that the threshold for invasion has not been reached. I loved the discussion in this case because it’s a basic benign vs malignant one. We spend a lot of time writing literature about really rare entities for which you will ask for a consultant’s help anyway. We don’t spend a lot of time discussing cases where the decision making is somewhat basic but REALLY crucial, and has a huge impact on patient care. So, if this lesion were flat, the differential diagnosis would include regressing KA vs hypertrophic LP vs well differentiated invasive squamous cell carcinoma. All are reasonable ideas; the threshold between pseudoepitheliomatous hyperplasia and well differentiated invasive SCC is a well known moving target. I came down on the side of NOT being invasive but this is a difficult case! Well done!

Great case and agree with your comments Uma.  I think there is so much learning from the routine sign-out. Like you I was favouring infundibular (epidermoid) cyst with scarring/inflammation etc. giving rise to the proliferating borders - however like many bench cases tucked away in the pile it's not easy!