PMC9794852_01
(A) Right supraorbital swelling at initial presentation. (B) Resolved right supraorbital swelling following 5 months of combined chemotherapy with imatinib.
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F1
Notable on examination was a right firm supraorbital swelling causing ptosis, with no overlying skin changes (Figure 1A). FIP1L1-PDGFRA gene fusion by FISH analysis was decreased to 2.5%. Five months following treatment, the supraorbital swelling had completely resolved (Figure 1B).
(A) Orbital MRI (coronal T1 fat sat postcontrast section) at initial presentation showing mass in the superior medial aspect of the right orbit (arrow). (B) Orbital MRI (Coronal T1 fat sat postcontrast section) following 5 months of combined chemotherapy with imatinib demonstrates marked improvement of tumor size.
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F2
There was a mild extension of the subcutaneous tissue in the supraorbital space, with compression of the right eye globe but no evidence of invasion of the sclera or retro-ocular extension (Figure 2A). Whole-body PET CT showed almost complete metabolic response, and the brain and orbital MRI showed almost complete resolution of the right orbital mass (Figure 2B).
(A) Bone marrow aspirate showing mostly eosinophils, Wright-Giemsa stain, 40x. (B) Biopsy from the orbital mass demonstrating heavy lymphoid infiltrate composed of small- to medium-sized lymphoblasts, hematoxylin and eosin stain, 40x. (C,D) PAX5 and TdT immunostains showing positive brown nuclear stain in the tumor cells, respectively, indicating that these cells are B-cell lymphoblasts 40x. (E) Rearranged PDGFRA gene (arrows). Rearrangement results from fusion of FIPL1 and PDGFRA after CHIC2 deletion.
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F3
Megakaryocytes were quantitatively normal (Figure 3A). An incisional biopsy of the supraorbital mass revealed B-cell lymphoblastic lymphoma (B-LBL) (Figure 3B-D). FISH test for FIP1L1-PDGFRA gene fusion was positive in 70% of the cells studied (Figure 3E).