A 42-year-old man suffers from marked pain in a toe that has been swollen for months. In addition, he reports shortness of breath on exertion during questioning.
The dorsoplantar radiograph shows abnormalities in the third toe on the left: the distal half of the proximal phalanx is enlarged and infiltrated with multiple microcysts arranged like a palisade. The enlarged middle and distal phalanxes show similar diffuse changes, with larger cysts in the centers in addition to microcysts.
The deformations as well as the diffuse cystic inclusions of the phalanges are also seen in MRI (hypointense in T1w and hyperintense in fatsaturated PDw). The expansion of the proximal phalanx is more intense. Incidentally, the head of the proximal phalanx II shows an intraosseous ganglion.
Question: What is the diagnosis?
