CASE REPORT: An 87-year-old male had a tumour nodule over the left parotid tail for about 20 years. Physical examinations revealed a 4.5 cm soft, non-tender and fixed mass. After the left parotidectomy, pathology confirmed the diagnosis of IDC arising within an intraparotid lymph node. The cystic component of the tumour was lined by single to multilayered ductal cells with micropapillary growth pattern. The solid part showed intraductal proliferation of neoplastic cells in solid, cribriform, micropapillary and Roman bridge-like structure. By immunohistochemistry (IHC), the tumour cells were positive for S-100, CK (AE1/AE3), mammaglobin, SOX10, and estrogen receptor (ER), with myoepithelial cell rimming highlighted by positive p63 and calponin IHC stains. The prognosis of this patient is excellent after complete excision.
DISCUSSION: The mechanism of salivary gland tumour arising in the intra-parotid gland LN was assumed to be related to salivary duct inclusion within the intraparotid gland LN which is a normal occurrence during embryology development. Although the terminology may raise some confusion about the relationship between IDC and conventional salivary duct carcinoma (SDA), they are different in immunophenotype and clinicopathologic features. IDC is characterised by S100 (+) ER (+) with predominant intraductal growth and excellent prognosis; while SDC features S100 (-) androgen receptor (+) with predominant invasive growth and aggressive behavior. Recent discovery of recurrent RET gene rearrangement in IDC but not SDC also supports that IDC is not precursor lesion of the SDC.
CASE REPORT: This paper describes a case of SOT affecting the anterior mandible of a 10-year-old Indian female. The patient was treated by local surgical excision and there has been no follow-up clinical record of recurrence 5 years after primary treatment. Histo?pathological examination revealed a solid, locally-infiltrative neoplasm composed of bland-looking squamatoid islands scattered in a mature fibrous connective tissue stroma and the diagnosis was SOT. Immunohistochemical evaluation showed positive reactivity of varying intensity in the neoplastic epithelial cells for Notch1, Notch3, Notch4, and their ligands Jagged1 and Delta1. Expression patterns showed considerable overlap. No immunoreactivity was detected for Notch2 and Jagged2.
CONCLUSIONS: Present findings suggest that Notch receptors and their ligands play differential roles in the cytodifferentiation of SOT.