Carcinoma Ex Pleomorphic Adenoma of the Parotid Gland: A Rare Case

Abstract

Cancer is a major cause of morbidity and mortality worldwide, with squamous cell carcinoma (SCC) being the most common type. Even though SCC is the major type of cancer found in the head and neck region, the salivary glands contribute to about 1/20 cases, of which 1/10 are said to be carcinoma ex pleomorphic adenoma (CXPA) type, and the parotid gland is found to be the most common origin of such cases. Although it usually arises later in life, it can grow rapidly, with local symptoms being late findings, if any. Even though fine needle aspiration cytology has low sensitivity for diagnosing such cancer, multiple/repeated biopsies can increase the yield and the accuracy of the test. Surgical resection is the main choice for treatment with postoperative radiation for select cases. Our case presented with CXPA with distant metastasis to multiple sites.

Keywords: brain metastasis; carcinoma ex pleomorphic adenoma; malignant pleural effusion; parotid tumor; squamous cell carcinoma; squamous cell carcinoma (scc).

Figure 1. CT scan of the head without contrast showing diffuse encephalomalacia (white arrows).

Figure 2. CT scan of the chest (left) showing pleural effusion (white arrow), unchanged from the prior CT scan of the chest (right).

Figure 3. CT scan of the head with contrast showing multiple ring-enhancing lesions suggestive of neoplasm/malignancy.

Figure 4. CT soft tissue neck with contrast showing salivary gland tumor centered within the left parotid gland with stranding of the surrounding subcutaneous tissues including the preauricular area as well as inflammatory changes extending toward the cartilaginous segment of the left external auditory canal with associated narrowing.

Figure 5. High and low power magnification images of parotid gland resection specimen showing an invasive carcinoma ex pleomorphic adenoma, with squamous cell carcinoma and high-grade adenocarcinoma components.

Figure 6. CT chest with contrast evident for right pleural effusion and basilar atelectasis and/or consolidation.

Figure 7. Pleural biopsy showing poorly differentiated epithelial cells infiltrate fibrotic pleural tissue. Tumor cells are positive for p40 and BER-EP4. Findings are consistent with squamous cell carcinoma.

Figure 8. CT scan of the abdomen with contrast showing a 1.6 cm hypodense lesion in the left lobe of the liver.

Figure 9. Positron emission tomography scan showing metabolically active foci in localizing to right lower lobe atelectasis and bilateral adrenal glands indicating neoplasm/malignancy.