PMC9879025_01
Initial FDG PET-MRI Images. (A) Coronal contrast enhanced T1 weighted MRI shows infiltrating subgaleal mass (arrows) with abnormal enhancement of the underlying calvarial marrow and nodular thickening of the dura (arrowheads). (B) The infiltrating mass is hypermetabolic on FDG-PET (arrows). (C) High-resolution CT of the skull reveals permeative erosions and slightly increased density of the involved parietal bone.
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MRI and positron emission tomography-computed tomography (PET-CT) demonstrated a 1.8x3.5 cm subgaleal hypermetabolic tumor of the scalp in the parietal area with permeative erosion of the adjacent calvarial bone and intracranial extension with extensive pachymeningeal involvement (Figure 1A-C).
Initial and Post-Treatment FDG PET-MRI. Composite fused FDG PET-MRI images at initial diagnosis and after treatment with R-CHOP alternating with R-MA. Coronal view of FDG PET maximum intensity projection (MIP) at initial diagnosis (A) demonstrates moderately hypermetabolic soft tissue in the scalp subcutaneous tissues with SUV max of 7.8 (red arrow). The subcutaneous tissue has transcalvarial extension and involvement of the underlying pachymeninges as seen on fused coronal FDG PET-MRI (B), T1 MRI (C), and FDG PET (D) (red arrows). Initial FDG PET MIP (A) also demonstrates hypermetabolic left preauricular lymph nodes and temporalis muscle involvement (blue arrow). Post-treatment fused FDG PET-MRI MIP (E) demonstrates complete resolution of the scalp subcutaneous tissues (red arrows) and lymphadenopathy (blue arrow) and is confirmed on coronal fused PET-MRI (F), T1 + contrast (G) and FDG PET (H) (red arrows).
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In addition, hypermetabolic changes were seen in three regional lymph nodes in the left preauricular region (Figure 2A). He achieved a complete remission (CR) after four cycles of CIT and has remained in CR for 4.25 years with no adverse sequelae from his lymphoma or lymphoma treatment (Figure 2A-H).
Pathologic Evaluation of Resected Tumor. The H&E sections (A, x 10) show the proliferation of neoplastic lymphocytes adjacent to the periosteal soft tissue (arrow); and neoplastic lymphocytes are large with open chromatin and prominent nucleoli; mitosis is brisk (inset, x 40). They are positive for CD20, CD10, BCL6, BCL2, with a high proliferative rate by Ki-67, 90% (B-F, x 20).
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The tumor was resected, and pathology revealed a diffuse proliferation of large, atypical lymphocytes in a fibrotic background adjacent to periosteal soft tissue and attached to the dura (Figure 3A and inset). The neoplastic lymphocytes were diffusely positive for CD20, CD10, BCL2, and BCL6 by immunohistochemistry, and 90% of cells stained positive for Ki-67 (Figure 3B-3F).