Case Number : CT0098 Adam_Bates

Aneurysmal fibrous histiocytoma with monster cells.
 

Atypical and aneurysmal fibrous histiocytoma. Complete excision is recommended.
 

Atypical aneurysmal fibrous histiocytoma
 

Agree. The monster cells are truly monstrous in this case!!
Not sure about the atypical mitoses in the last image though...should that be concerning?

I agree with atypical aneurysmal fibrous histiocytoma. If there is history of irradiation in that anatomical region, angiosarc has to be r/o.
 

"Symplastic" AFH
 

I called it atypical fibrous histiocytoma and cited the reference below. It is certainly scary but I think atypical mitotic figures are to be expected in tumours with monster cells (e.g. trichoepithelioma, Spitz naevus) and do not necessarily predict a malignant outcome.
 

I don't think I can refute the argument based on our current knowledge. Cases such as this challenge our concepts tremendously and I certainly don't feel at peace at all but I have to sleep at night so must be pragmatic and explain that the diagnostic label is one thing, predicting the potential behaviour is another thing altogether. In this case the group label suggests a low risk for metastasis. Whether there are individual tumour or host factors that affected the behaviour in the lesions that did and did not metastasise remains to be determined. Perhaps some are essentially benign and do not have any inate capacity (at the time of removal) to metastasise and kill and some are malignant and do have that capacity. I don't think anyone can currently answer these questions.