Presentation
Right forehead swelling for the last 4 years. No history of trauma, headache, or seizures.
Patient Data
A defect is seen in the right frontal bone. An associated hypoechoic soft tissue lesion with irregular echogenic posterior borders is seen in the right frontal region (at the site of bone defect). No significant vascularity is seen in the soft tissue component on doppler ultrasound examination.
Two osteolytic lesions with associated small soft tissue components are seen in the right frontal and left posterior parietal bones; nature ? Possible imaging differential diagnosis includes eosinophilic granuloma, meningiomas, and lytic bone metastases.
Two small soft tissue signal intensity calvarial lesions involving both the inner and outer tables are noted in the right frontal and left posterior high parietal regions. These lesions have associated small epidural components. The lesions show vivid enhancement on the post-contrast study.
Evidence of previous right frontal craniectomy is noted. A small focal hypodensity is seen in the underlying brain parenchyma which likely represents postoperative change. Redemonstration of the left parietal bone lesion with soft tissue component which appears relatively small now when compared with the previous study.
Case Discussion
Histology report
Procedure: Right frontal craniectomy with total excision of the right frontal skull lesion.
Microscopic description: The lesion comprises foamy histiocytes in a background of fibroblastic reaction and plasmacytic infiltration. The foamy histiocytes appear to have ingested lymphocytes, plasma cells, and red blood cells. The histiocytes show strong immunoreactivity for S100 and CD68. They appear to be nonreactive to CD1a, but this test is inconclusive because of a lack of appropriate control. The plasma cell infiltrate is polyclonal staining for both LAMBDA and KAPPA light chains by immunohistochemistry.
Final diagnosis: The histological picture favors extranodal Rosai-Dorfman disease over eosinophilic granuloma. There is no evidence of metastatic malignancy.
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