case_images: PMC8803631_01
case_images: Bilateral cervical giant cysts (A), left cyst enlarged after chemotherapy (B), and surgical excision of the right neck mass (C). MRI of a tumor before surgery (D-F) and after (G-I) chemotherapy: T1-weighted images (D, G), Ga-enhanced T1-weighted images (E, F, H, I).
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case_images: Physical examination revealed two tender, fixed, and painless masses with a clear boundary (a ~7- x 6-cm mass in the left submandibular area and an ~8- x 7-cm mass in the right submandibular area;  Figure 1A ). Magnetic resonance imaging (MRI) ( Figures 1D, E ) revealed bilateral cervical cystic lesions and multiple enlarged bilateral cervical lymph nodes. The mass was cystic and filled with thick, dirty yellow fluid, with a ~1-cm-thick cystic wall ( Figure 1C ). The patient underwent a second surgery on August 1, 2021 because the left lateral cervical mass ( Figure 1B ) was not significantly reduced and pain was experienced when swallowing. MRI of the neck after chemotherapy ( Figures 1G-I ) showed that the cyst had again increased in size and the cystic wall was thinner than before ( Figures 1D-F ).
case_images: By H&E staining results: the neoplastic cells exhibited cytological atypia, hyperchromatic nuclei, prominent nucleoli, and a high mitotic rate (A). Immunohistochemical staining for CD1a + (B), S-100 + (C), Langerin+ (D), and CD56+ (E); the Ki67 proliferation index was ~60% (F). All magnifications x40. Electron micrograph showing a large kidney-shaped nucleus (G) and typical Birbeck granules (H) in neoplastic cells. EBER in situ hybridization indicating positive signals in the nuclei of background lymphocytes (I), x20.
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case_images: The neoplastic cells exhibited cytological atypia, hyperchromatic nuclei, and prominent nucleoli, and nuclear grooving was observed in some of them ( Figure 2A ). Immunohistochemical studies revealed that the malignant tumor cells were positive for CD1a ( Figure 2B ), S-100 protein ( Figure 2C ), and Langerin ( Figure 2D ). There was variable expression of CD56 ( Figure 2E ), cyclin D1, CD4, CD68, and CD163. Mitoses were frequently identified, and the Ki-67 proliferative index ( Figure 2F ) was ~60%. Electron microscopy demonstrated the presence of a large kidney-shaped nucleus ( Figure 2G ) and typical Birbeck granules ( Figure 2H ), with unique striated cytoplasmic organelles characteristic of neoplastic cells. CD56, CD68, and CD163 expression became negative in neoplastic cells. Chromogen in situ hybridization for the Epstein-Barr encoding region (EBER) of background lymphocytes ( Figure 2I ) was positive.
case_images: HRCT of the chest, showing numerous variably sized pulmonary cysts that were confluent in some places (A-C); the cysts became larger and thin-walled after chemotherapy (D, E). PET-CT examination of the patient's general condition. Signal from the left neck mass and multiple small lymph nodes (F), pulmonary cystic lesions (G), and liver (H). There was no signal from bone (I).
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case_images: High-resolution computed tomography (HRCT) of the chest before chemotherapy ( Figures 3A-C ) showed numerous variably sized pulmonary cysts that were confluent in some places, and HRCT of the chest after chemotherapy ( Figures 3D, E ) showed that the pulmonary cysts were enlarged and thin-walled. The patient's general condition was assessed by positron emission tomography-computed tomography (PET-CT) ( Figures 3F-I ). A 90 x 85-mm mass was detected in the left neck with a maximal standardized uptake value (SUVmax) of ~5.7 ( Figure 3F ); the multiple small lymph nodes located close to the mass had an SUVmax of ~5.5. Figure 3G ). Fluorine-18 fluorodeoxyglucose (FDG) uptake in the LCS lesions was lower than in prior reports (cases 19, 24, and 25 in 