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.
METHODS: We conducted a cross-sectional study by using 29 archived formalin-fixed paraffin embedded tissue blocks of DLBCL. All the samples were evaluated for the subgrouping of COO DLBCL was determined by expression of CD10, BCL6 and MUM1 based on Hans classification. In addition, expressions of c-MYC, BCL2 and BCL6 were detected by IHC.
RESULTS: Among the 29 cases, MYC, BCL2 and BCL6 proteins were detected in 72.4%, 62.1% and 62.1% of patients, respectively. Concurrent expression (c-MYC positive/BCL2 positive and/or BCL6 positive) was present in 58.6% of patients. 34.5% were categorised as germinal centre like (GCB) subgroup and 65.5% were categorised as nongerminal centre like (non-GCB) subgroup. Among the clinicopathological features, the double/triple protein expression lymphoma was significantly associated with elevated LDH level (p=0.018), IPI score (p=0.003), Ann Arbor stage (p=0.011) and complete response rate (p=0.011).
CONCLUSION: Double/triple protein lymphoma was strongly associated more adverse clinical risk factors. Thus, analyses of MYC, BCL2 and BCL6 expression by IHC represents a rapid and inexpensive approach to risk-stratify patients with DLBCL at diagnosis.