Understanding primary parotid squamous cell carcinoma - A systematic review.

Area of Science:

• Oncology
• Head and Neck Surgery
• Pathology

Background:

• The incidence of primary parotid squamous cell carcinoma (SCC) is uncertain and potentially overestimated.
• Existing literature lacks standardized diagnostic criteria for parotid SCC.

Purpose of the Study:

• To systematically review the diagnosis, etiology, and incidence of primary parotid SCC.
• To analyze studies evaluating primary parotid SCC to clarify its characteristics.

Main Methods:

• Systematic literature search of Medline, EMBASE, and Cochrane Library.
• Inclusion of 14 observational retrospective studies.
• Narrative synthesis of findings.

Main Results:

• Primary parotid SCC incidence ranges from 1.54 to 2.8 cases per million person-years.
• A significant proportion (30%-86%) of clinically diagnosed primary parotid SCC were secondary to lymph node metastasis.
• Histological features suggesting primary SCC include confinement to parotid parenchyma without skin communication and absence of mucin.

Conclusions:

• Primary parotid SCC is a rare diagnosis of exclusion.
• Distinguishing primary from secondary SCC necessitates thorough clinical assessment (endoscopy, imaging) and histopathological scrutiny.
• Accurate differentiation impacts initial treatment and long-term patient follow-up.