PMC10359696_01
(case 2): Ceruminous gland adenoma in the bony portion of the left external auditory canal. Coronal CT showed a soft mass, the tympanic bone was mildly involved and was highlighted by a red arrow(a). Coronal T2WI showed a high signal intensity in the deep part of the EAC.
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The site of the tumors is summarized as follows: in six cases (6/9, 67%) the lesions were located only in the cartilaginous portion of the external auditory canal (EAC); in one case (1/9, 11%) the lesion was located only in the bony portion of the external auditory canal (EAC) ( Figure 1 ); in one case (1/9, 11%) the lesion was originated from the cartilaginous portion with extension into the bony part of the EAC; in another case (1/9, 11%), the tumor located in the cartilaginous portion and protruded out from the EAC. On temporal HRCT, all of the lesions exhibited isoattenuating soft tissue masses in the EAC, one mildly involved the tympanic bone ( Figure 1 ).
(case 8) An 84-year-old man had a 36mm max diameter ceruminous pleomorphic adenoma in the right EAC protruding out from the EAC and extending to the parotid (behind the mass, cholesteatoma was found in the EAC). CT: (A, B) calcified foci (black arrow) and heterogenous enhancement in the tumor. MRI (C-F):T1 low intensity (C), T2 intermediate and high signal intensity (D), DWI intermediate signal intensity (E) (behind the mass, cholesteatoma appeared as high intensity); the mass showed edge enhancement (black arrow) and was adjacent to the parotid (star) on coronal enhanced T1 (F). The mass is a lobulated solid mass on the gross appearance (G).
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On DWI of five cases, all tumors appeared as intermediate signal intensity, but in two of them high signal intensity of cholesteatoma was also found deep to the tumor in the EAC ( Figures 2D, F ).  Figure 2  showed that the tumor was adjacent to the parotid gland, however, the  Figure 2F  revealed the tumor was originated in the EAC, there was a gap between the tumor and the parotid gland, and  Figure 2G  revealed the integrity of the tumor capsule.
(A) (case 5) Ceruminous gland adenoma of the external auditory canal, evaluation with hematoxylin-eosin staining. The neoplastic proliferation of ceruminous glands is visible. The glandular epithelium is bilayered. Abundant cytoplasm is seen in the luminal cells, which show focal decapitation secretion and contain ceroid pigment (40x). (B) (case 8) Histological findings of ceruminous pleomorphic adenoma of the EAC showing the glandular epithelial component and myxofirous stroma(40x). (C) (case 9) Ceruminous syringocystadenoma papilliferum of the external auditory canal, evaluation with hematoxylin-eosin staining. Note papillae lined by glandular epithelium projecting into a cystic lumen(40x).
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Among them, six cases were diagnosed as ceruminous gland adenoma ( Figure 3A ), two cases were diagnosed as ceruminous pleomorphic adenoma ( Figure 3B ), one case was diagnosed as ceruminous syringocystadenoma papilliferum ( Figure 3C ).