Lymphoplasmacytic lymphoma was diagnosed histologically from bone marrow biopsy, and this process was therefore assumed to be the same pathology.

Lymphoplasmacytic lymphoma is a rare non-Hodgkin lymphoma.  There are several types, but the commonest is Waldenström's macroglobulinemia.

This appearance in the orbits is usually secondary to non-Hodgkin lymphoma. Orbital pseudolymphoma or thyroid orbitopathy predominantly involve the extraocular muscles, without extensive abnormal tissue in the retro-orbital fat.