case_images: PMC11187072_01
case_images: Images of initial imaging examinations. Axial MRI with fat-suppressed T2-weighted image (A, E), T1-weighted image (B, F) fat-suppressed contrast-enhanced T1-image (C, G), and PET-CT images (D, H). Dilated duct filled with fluid signal, and small nodules on the ductal wall show slight hyperuptake on PET image (A, D, arrowhead). Note the small focus at the orifice region with hypointense T2 and hyperintense T1 signal (A-C, dotted arrow). A heterogeneous mass with enhancement on contrast-enhanced MRI (G) and slight hyperuptake on PET (H) in the parenchyma were detected (E-H, arrow). Nodules on ductal wall and parenchymal mass showed different signal entity.
case_images: fonc-14-1324214-g001.jpg
case_images: PMC11187072_01_fonc-14-1324214-g001.jpg
case_images: f1
case_images: Stensen's duct was confirmed, and a hypointense nodular focus was observed in the duct orifice region ( Figures 1A-D ). Some small nodular foci were detected in the dilated ductal wall, and these nodules showed hypointense T2 and enhancement signals. T2 and hypointense T1 signal intensity ( Figures 1E-H ). The low-signal nodule at the orifice was thought to be sialolith causing obstruction and sialadeitis in the NS ( Figures 1A, B ). PET-CT images showed minimal hyper-uptake in the parotid parenchyma, hindering a malignancy diagnosis ( Figure 1H ).
case_images: Contrast-enhanced CT images obtained after 1 month (A-C). Nodular enhancing masses along the dilated ductal wall were enlarged (A). No calcified focus at the orifice region on bone filtered reconstruction (B) dotted arrow. Parenchymal lesion showed heterogeneous enhancement (C) white arrow. Pre-operative images (the images 3 months after the initial MR) of axial fat-suppressed T2-weighted MR image (D), T1-weighted MR image (E), contrast-enhanced CT images of axial (F), and coronal (G). An enlarged ductal wall and enlarged nodular mass (arrowheads) were confirmed (D-F). Note the hypointense T2 signal and hyperintense T1 signal of ductal wall melanoma (D, E). Coronal contrast-enhanced CT image shows an enlarged ipsilateral cervical lymph node that is revealed as metastasis (black arrow, (G).
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case_images: PMC11187072_01_fonc-14-1324214-g002.jpg
case_images: f2
case_images: In the contrast-enhanced CT images obtained after a month, nodular enhancing masses along the dilated ductal wall were confirmed ( Figure 2A ), but there was no calcified focus at the orifice ( Figure 2B ). The heterogeneously enhancing parenchymal mass showed a mixture of highly attenuated areas similar to vessel and a low attenuated lesion with faint margin ( Figure 2C ). On pre-operative CT and MR images obtained 3 months after the initial imaging, the nodular lesion on the ductal wall was enlarged ( Figure 2D ), the hyperintense T1 signal ( Figure 2E ) and enhancement ( Figure 2F ) became remarkable. In addition, a positive lymph node not detected in the previous exams was enlarged to level IIa ( Figure 2G ).
case_images: Representative histopathologic features strongly suggesting that malignant melanoma originated from the ductal epithelium. (A, B) Malignant melanoma of the parotid duct. Intraluminal masses arising from the ductal epithelium. (C) Large polygonal tumor cells had melanin pigments and immunoreactivities for HMB-45. (D) The remaining ductal epithelial cells were detected by the immunostaining with cytokeratin 7 (black arrows). (E) Tumor masses (asterisk) arising from the ductal epithelium (scale bar = 3mm). Inserted box area is magnified and shown in (F-H). (F) Hyperchromatic, atypical cells were observed in the ductal epithelium. (G) Proliferating atypical melanocytic cells in the epithelium were positive for HMB-45. (H) The intact ductal epithelial cells were positive for cytokeratin 7. Hematoxylin and eosin staining (A-C, E, F) and immunohistochemical staining (D, G, H); Olympus BX45 microscope; Spot image capture software (Spot Imaging, Sterling Heights, MI, USA). HMB45.
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case_images: PMC11187072_01_fonc-14-1324214-g003.jpg
case_images: f3
case_images: One was a tumor mass that had grown into the lumen from the epithelium of an enlarged salivary gland duct ( Figures 3A, B, E ). The tumor cells had dark brown melanin pigments in hematoxylin-eosin staining ( Figure 3F ) and showed diffuse positive immunoreactivity for HMB-45 ( Figures 3C, G ). The remaining ductal epithelial cells of the affected duct were positive for cytokeratin 7 ( Figures 3D, H ).