Expression of α‑smooth muscle actin in benign and malignant salivary gland tumors: An immunohistochemical study

*, Mahalakshmi Ravi and Boaz, Karen and *, Srikant N and Lewis, Amitha J and *, Mukul Prasad and Yellapurkar, Swetha (2018) Expression of α‑smooth muscle actin in benign and malignant salivary gland tumors: An immunohistochemical study. Indian Journal of Pathology and Microbiology, 61 (4). pp. 479-484. ISSN 03774929

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Background and Objectives: Myoepithelial cells (ME) are known to contribute in the patterning of salivary gland neoplasms (SGN) and possess cytoplasmic smooth muscle actin (SMA) revealed by alpha SMA (α‑SMA). The present study aimed to assess the expression of α‑SMA in selected benign and malignant SGN (pleomorphic adenoma [PA], mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ACC), and polymorphous low‑grade adenocarcinoma (PLGA). Materials and Methods: The intensity and pattern of expression of α‑SMA were studied in 25 cases of SGN’s ACC (n = 7), MEC (n = 8), PA (n = 8), and PLGA (n = 2), and correlated with the histological patterns. Results: Maximum expression of α‑SMA in the epithelial compartment was seen in ACC, followed by PA, whereas MEC and PLGA showed completely negative staining. The connective tissue expression was mild in ACC and MEC. The myxoid stroma of PA with “melting” pattern was weakly positive for α‑SMA. The stroma in PLGA showed complete negativity. In ACC, α‑SMA‑positive cells were lining the cribriform spaces, small islands, and dispersed within large islands. Small nests showed complete positivity for α‑SMA. Interpretation and Conclusion: In ACC, α‑SMA expression supports the involvement of ME in epithelial organization explaining the histological patterns seen. In PA, the expression correlates with the predominantly secretory nature of ME. The absence of epithelial positivity in MEC and PLGA suggest that ME has less role to play in their histogenesis. The weak stromal positivity observed in MEC and ACC may be attributed to the positive immunoreactivity of myofibroblasts playing a role in modulating the course of SGN’s.

Item Type: Article
Uncontrolled Keywords: Adenoid cystic carcinoma, alpha smooth muscle actin, histogenesis, myoepithelial cells, tumour patterning
Subjects: Dentistry > MCODS Mangalore > Oral Pathology
Depositing User: KMCMLR User
Date Deposited: 24 Oct 2018 06:07
Last Modified: 24 Oct 2018 06:07

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