This is a case of a young adult woman who was found dead at home. Her history is remarkable for drug use as well as an uncertain report of a physical attack by her boyfriend a couple of weeks ago (not reported and no medical records).
At autopsy, she had a very high postmortem level of fentanyl and no immediately life-threatening illness or trauma. But… on radiographic examination, there was an odd lesion of the right humerus. In light of the possible history of violence, I dissected the arm and got a sample of what appeared to be callus on gross exam. Here’s the pertinent portion of the radiograph:
On histologic exam, it was an expansive unencapsulated soft tissue growth within the bone:
On closer view, it consists primarily of spindle cells with some areas of more dense fibrosis:
Other areas are more loose with greater inflammation, mostly plasma cells:
At higher power, the spindle cells are plump fibroblasts with open chromatin and occasional nucleoli. The inflammatory cells are mostly plasma cells with a fair number of lymphocytes. Nothing looks atypical/dysplastic.
These findings are characteristic of an inflammatory myfibroblastic tumor, called an inflammatory pseudotumor back in the days when I was a young pathologist. While there are malignant variants, this is characteristically indolent and does not metastasize. The diagnosis characteristically is confirmed with ALK1, vimentin, and keratin expression, but since this had nothing to do with the cause of death, I made the presumptive diagnosis based on H&E and let it go.