Contributed by Vincent A. van Vugt1, Aditya Kesari1, Karra A. Muller, MD, PhD2, Bob Carter, MD, PhD3, Scott R. Vandenberg, MD, PhD2, Santosh Kesari, MD, PhD1*
1Department of Neurosciences, Moores Cancer Center, University of California, San Diego, La Jolla, CA, 92093
2Department of Pathology, Neuropathology Division, University of California, San Diego, La Jolla, CA, 92093
3Department of Neurosurgery, University of California, San Diego, La Jolla, CA, 92093
CLINICAL HISTORY AND IMAGING
A 22-year old female presented with a five-week history of right retroorbital pain and eyelid swelling. She denied headaches, loss of vision, focal neurological symptoms or ocular symptoms. On exam she had tenderness over right eyebrow and temporal bone. Her past medical history was unremarkable. An ophthalmologist initially saw her and a CT-scan was ordered. The scan showed an orbital bony lesion, which contained a solid component as well as a fluid level without calcifications or a bony matrix (Figure 1). A subsequent MRI revealed a contrast-enhancing lesion eroding the roof of the orbit posterolaterally on the right (Figure 2). Involvement of the inner table of the temporal bone was also demonstrated on MRI. The patient was referred to our center at this time for further evaluation. A CT angiogram was performed to assess the vascularity of the lesion and whether or not any preoperative embolization would be of utility. On the angiogram no vascular abnormalities could be identified intracranially. One month after her initial presentation she successfully underwent a bifrontal craniotomy with resection of the orbito-temporal lesion and placement of a prosthetic right orbital roof.
GROSS AND MICROSCOPIC PATHOLOGY
Gross examination revealed non-descript brown-tan and hemorrhagic soft tissues adherent to fragments of partially eroded bone. A separate specimen submitted as "dural margin" was composed of brown, hemorrhagic, lobulated, and somewhat cystic soft tissue adherent to the outer surface of normal dura. Hematoxylin and eosin stained sections of the specimens showed nodular aggregates of large mononuclear cells (Figure 3) with high nuclear-to-cytoplasmic ratios characterized by indented and clefted nuclei (Figure 4). These cells contained amphophilic cytoplasm, had distinct cytoplasmic borders, and showed positivity for both S-100 and CD1a by immunohistochemistry (Figures 5 and 6, respectively). These nodules of atypical cells were accompanied by an exuberant mixed inflammatory infiltrate composed of many lymphocytes, plasma cells, and eosinophils (Figure 7). Occasional multinucleate giant cells were seen throughout the inflammatory infiltrate (Figure 8). Scattered CD68-positive histiocytes (Figure 9) that were negative for both S-100 and CD1a were seen adjacent to atypical cells within the lesional nodules and within the mixed inflammatory infiltrate. What is your diagnosis?