Case Number : Case 2207 - 22 November 2018 Posted By: Dr. Richard Carr

CD 68?

S100?  This is a very nice example of Rosaj Dorfmann Disease. 

Differential includes generalized reticulohistiocytoma and rosai dorfman disease. IHC helps

xanthomatous lesions, I am not seeing Touton cell

like to get IHC done and lipid profile to see whether it is normolipemic xanthomas and consider xanthoma disseminativum as the histopathology can show only xanthogranuloma more clinical information needed

Agree whit Vincenzo, it looks like Rosai-Dorfmann. But the clinical scenario is quite odd for me. Maybe Multicentric Reticulohistiocytosis is a better diagnosis.

I would definitely do S-100. Every time I see a histiocytic lesion in which the histiocytes a vesicular nucleus with a relatively prominent nucleolus like in the last 2 pictures, I always think of Rosai-Dorfman because most histiocytes have a rather dark, small pyknotic nucleus. But agree, reticulohistiocytosis would be my second guess.

IHC is posted. Any additional comments?

Aberrant(but well known) positivity for CD30. 

The ALCL lymphohistocytic variant is whole another thing ( morphology is still important in our job). Nice case of RDD. Thanks Richard. 

is it ALCL then or rosai dorfman with aberrant CD30

It really looks like RDD; I was not aware of this aberrant CD30 positivity in RDD

Agreed for Rosai Dorfman. Well done. I did not over interpret the CD30!