Case Number : Case 1343 - 17 August Posted By: Guest

This lesion has a biphasic appearance with peripheral spindle cells with eosinophilic cytoplasm and central nodular areas with basophilic cells in a myxoid/?chondroid matrx.
?Solitary Myofibroma

Agree with myofibroma.

Nice suggestion of myofibroma. I did not think of it, I thought of cellular neurothekoma with prominent myxoid stroma. The clinical impression of a melanocytic nevus does not fit with the usual clinical presentation of solitary myofibromas. I am not expert in this area and I am looking forward to the correct diagnosis.

Here is my microscopic description:

There is a circumscribed lesion that contains small epicenters of somewhat myxoid areas that have epithelioid cells within them, and in the "fibrous" zones between the myxoid areas, the cells are slightly smaller. They are all uniform throughout the entire field however. There is no nuclear pleomorphism in the lesion. Immunostains show that this lesion is strongly positive with S100 protein in nuclei and cytoplasm of the small cluster-like zones, while CD63 is weakly positive. Melan-A, neuron specific enolase, D2-40, EMA, actin, CD10, and CD68 are all negative or very diminished. Ki67 (clone 30-9) has an index of less than 1% positive in my opinion.

And here is my diagnosis:

[b]-- NERVE SHEATH MYXOMA[/b]

Very difficult case today! Diffuse S100 obviously points to a neural tumour and rules out the other possibilities considered. But Dr Hurt, isn't the tumour too cellular for a nerve sheath myxoma? Would you consider a variant of dermal schwannoma (plexiform/epithelioid) in the differential ??

Arti, I see your point, and perhaps you're right.