Parotid salivary gland calculi

Parotid calculi are less common than calculi in the submandibular gland because the former is primarily serous.

The patient presents with swelling and pain, aggravated by eating, but subsiding within the next hour or so after the meal. Palpation of the gland confirms that it is enlarged and should be done on both sides for comparative purposes.

Calculi must be differentiated from stenosis of the duct caused by repeated trauma and fibrosis. Plain X-rays may reveal larger stones but the soft tissue image of the cheek makes this method less suited for the detection of smaller ones. Sialograms are more likely to be able to reveal the stones but still may be difficult to interpret. Other investigative options include ultrasonography, computed tomography scanning and magnetic resonance imaging

• plain X-rays:
  • occlusal and lateral-oblique views demonstrate most calculi
  • 20% of calculi are radiolucent and hence undetectable
• sialiography - contrast radiography of the duct system:
  • distinguishes calcification not related to the gland and its duct
  • sialography allows examination of the architecture of the salivary gland and duct
• ultrasonography, computed tomography and magnetic resonance imaging are particularly useful in evaluating masses in the salivary glands (1)
  • ultrasonography
    • can be used to differentiate between solid versus cystic lesions of the gland
    • can be used to differentiate intrinsic from extrinsic disease
    • helpful in identification of abscess formation
  • computed tomography scanning
    • useful in differentiating intrinsic versus extrinsic glandular disease
    • can be used in defining abscess formation versus phlegmon
    • limited usefulness in evaluation of ductal system unless combined with simultaneous sialography
  • magnetic resonance imaging
    • does not allow evaluation of the ductal system, and it is not helpful in defining calcifications
    • excellent tool for soft tissue definition (invaluable in instances of suspected neoplasia)

Stones close to the duct orifice are removed by ductal dilation and massage. Those in the gland are treated by excising the gland.

Notes:

• the majority of salivary calculi (80% to 95%) occur in the submandibular gland, whereas 5% to 20% are found in the parotid gland
• sialothiasis rarely affects the sublingual gland and the minor salivary glands are rarely (1% to 2%) (2)
  • sialolithiasis can occur at any age - however most cases occur in patients in their third to sixth decade. Sialothiasis rarely occurs in children
  • males and females are equally affected

Reference:

1. Can Assoc Radiol J. 1993 Oct;44(5):342-9.
2. Bodner L. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002 Sep;94(3):320-3.