Case Number : Case 2191 - 1 November 2018 Posted By: Raul Perret

Dermatofibroma with granular cell change. 

Definitely a cutaneous neoplasm with granular cytoplasm such as DF with granular cell change as Anil suggested (although I would expect to see some DF-like areas somewhere in the tumor to make that diagnosis just on H&E). A lot of tumors of the skin can have granular cytoplasm and the one that we usually place on top of the differential diagnosis list is granular cell tumor which is S-100 positive. This granular cell tumor, however, shows a little more nuclear polymorphism, vesicular nuclei, and kind of prominent nucleoli compared to the usual granular cell tumor. Therefore, I also would like to order NKI-C3 (I don't have it but Raul probably does because he is kind of soft tissue guy) and Alk-1 (maybe do FISH) in addition to S-100 .

Granular cell tumor

Granular cell tumor. The granules are aggregate in small complexes!!!

My spot diagnosis is Granular cell tumor. 

The other possibilitys are Cellular Neurothekeoma and DF whit granular cell changes (as other already mentioned) 

Nice case of ALK-positive epithelioid fibrous histiocytoma with granular cell cytoplasma. There is ALK overexpression by IHQ and some FISH rearrangment.

Interesting what Vincenzo wrote " The granules are aggregate in small complexes!!! ". Indeed there are eosinophilic globules surrounded by a halo in the cytoplasm of some neoplastic cells. I think they are called pustulo-ovoid bodies. In conjunction with the immunonegativity of the tumor for S-100, I think this is an example of cutaneous non neural granular cell tumor. The immunopositivity for Alk-1 is also very interesting in this tumor but I think Raul is better than I to explain it.

Hey guys, yes this is a case of epithelioid fibrous histiocytoma with granular cell change.

Granular cell change is actually a pattern that indicates massive acumulation of lysosomes in the cells' cytoplasm and can be seen focally or diffusely in many different neoplasms (BCC, muscular neoplasms, dermatofibromas, melanoma, etc.).

A subgroup of these tumors, located in the skin and lacking S-100 expression, were previously reported as: "Dermal non-neural granular cell tumours" or "primitive polypoid granular cell tumours".

Our team and others noticed that appart from the granular cell change, many clinical and morphological features were shared between these tumors and epithelioid fibrous histiocytoma. By performing ALK immunohistochemistry and FISH we demonstrated that a group of these Non neural granular cell tumors of the skin were actually EFH variants. This finding was recently confirmed in a larger series.

Hope you guys liked the case.

Raul, great case.

So you would call this tumor epithelioid fibrous histiocytoma with granular cytoplasm instead of primary cutaneous non neural granular cell tumor because I think this type of tumor is probably classified as non neural granular cell tumor in the WHO classification.

Wow...what a case and great learning points!

Awesome case Raul!

Ditto!