Case Number : Case 1896 - 04 Sept - Dr Limin Yu Posted By: Guest

A broad spectrum of Ddx here: low grade leiomyosarcoma, cellular neurothekeoma, fibromatosis variant of plexiform fibrohistiocytic tumor and, finally, the one I'm thinking of as the clinics-pathologically more consistent: primitive non neural granular cell tumor ( Le Boit ).

I thought of atypical granular cell tumor for immunos, neural or non-neural. I do not have experience with non neural granular cell tumor so I need to read the articles. Nevertheless, I think they are hard to differenciate from atypical cellular neurothekeoma based on the phenotype and morphology? 

Yes, Raul, hard to differentiate from CNT, but I think there is a typical "granular" cytology in this particular case (fig15 and last fig), with pseudo vacuoles. Large cytoplasmic granules, surrounded by a clear halo. In Weedon's book these granules are named "pustule-ovoid bodies of Milian". 

What do you think about?

I go for a metastatic lesion.

2 hours ago, vincenzo polizzi said:

Yes, Raul, hard to differentiate from CNT, but I think there is a typical "granular" cytology in this particular case (fig15 and last fig), with pseudo vacuoles. Large cytoplasmic granules, surrounded by a clear halo. In Weedon's book these granules are named "pustule-ovoid bodies of Milian". 

What do you think about?

I had the same impression as you about the granules, as a matter of fact it was one of the points that made me favour GCT. We usually see a central eosinophilic granule surrounded by the vacuole but I still think they are Milian bodies as you remark. Cellular neurothekeoma can have a granular cytoplasm too and is usually a commom differential of GCT. On the other had, I have read that Milian bodies contain Myelin so this would go against a non-neural GCT, do you agree?

I have read that Milian bodies contain Myelin so this would go against a non-neural GCT, do you agree?

Yes agree...

...But the questions are many, and for now I will only support the diagnosis of primitive non neural GCT, because of the clinical presentation (pyogenic granuloma-like) and the strictly fascicular pattern, in opposite the usual nested or plexiform pattern of CNT. I would like to know if the S100 is positive...

Primitive non neural GCT.

Primitive non neural granular cell tumor  is a great thought, fitting the clinical impression. The other thought was epithelioid cell histiocytoma; so ALK immunostain was performed and it was positive (see attached image). 

This case was signed out as epithelioid cell histiocytoma. The ALK rearrangement was discussed in this article https://www.ncbi.nlm.nih.gov/pubmed/25857825