Case Presentation
An 80-year-old Caucasian woman came to the hospital due to swelling on the left side of her face. It had been growing gradually for two months. She didn’t experience difficulty swallowing, pain when swallowing, fever, or weight loss. There were no previous issues with the parotid gland. Upon examination, a tender swelling about 2.5 cm in size with unclear edges was observed over her left parotid gland. Her temporomandibular joint showed no abnormalities.
Tests revealed a hypoechoic mass in her left parotid gland, approximately 2.8 cm in size, with poorly defined borders on ultrasound. Magnetic resonance imaging showed a distinct cystic and/or necrotic mass in her left parotid gland, measuring 3.4 × 3.0 × 3.0 cm. The lesion affected the superficial lobe of the parotid gland. It extended through the stylomandibular tunnel to involve the lateral aspect of the deep lobe. The MRI indicated varied signal intensities, with areas of cystic change or necrosis.
Investigations
The fine needle aspiration, guided by ultrasound and using both 21- and 25-gauge needles, revealed results categorized as atypia of undetermined significance classification 3. Examination of the smears revealed clusters and individual cells exhibiting an elevated nucleus-to-cytoplasm ratio, along with some hyperchromasia. These findings were set against a backdrop of cellular debris, including lymphocytes and neutrophils, indicative of potential necrosis. Although an inflammatory or cystic condition was plausible, the specter of primary or metastatic malignancy lingered due to inconclusive evidence.
Management
Subsequently, the patient underwent a left total parotidectomy. This was accompanied by left-selective neck dissections targeting levels 2 and 3. It was followed by soft tissue reconstruction using the sternocleidomastoid muscle. An intraoperative evaluation confirmed the presence of adenocarcinoma with a poorly differentiated component. Examination of the deep lobe unveiled a 3.5 × 2.9 × 2.9 cm lesion characterized by both carcinomatous and sarcomatous elements infiltrating adjacent soft and adipose tissues. The carcinomatous component exhibited features typical of adenoid cystic carcinoma, while the sarcomatous element displayed high-grade spindle cell morphology with areas of necrosis and sporadic chondroid differentiation. This comprehensive assessment painted a complex clinical picture, demanding diligent management and further investigation.
Analysis of Carcinoma
Immunohistochemical analysis of the tumor revealed positivity for CAM 5.2, CD117, p63, SMMH, p40, CK7, pancytokeratin AE1/AE3, and GATA-3 in the adenoid cystic carcinoma component. Moreover, androgen receptors, CD57, and calponin showed negative results. Conversely, the sarcoma component exhibited positivity for vimentin and S-100, particularly highlighting foci of chondroid differentiation. The Ki-67 proliferation index ranged from 50% to 70% in the sarcomatous region. Pleomorphic adenoma foci were absent, raising the possibility of a carcinosarcoma ex-pleomorphic adenoma or a de novo carcinosarcoma.
Fortunately, lymph nodes tested negative for metastatic carcinoma. The patient had radiotherapy targeting the tumor bed and skull base due to the potential for perineural invasion by the adenoid cystic component. This treatment strategy aimed to mitigate the risk of recurrence and ensure the best possible outcome for the patient’s condition.
Discussion
Carcinosarcoma, also known as malignant mixed tumour, is a rare type of tumour found in the salivary glands, characterized by distinct carcinomatous and sarcomatous components. It comprises a small fraction, estimated at around 0.04% to 0.16%, of all salivary gland tumors. Typically, these tumors occur most frequently in the parotid gland and can either develop de novo or arise from an existing pleomorphic adenoma. The common carcinomatous elements include adenocarcinoma, undifferentiated carcinoma, and squamous cell carcinoma.
This case highlights a unique instance where adenoid cystic carcinoma constitutes the carcinomatous component, accompanied by chondrosarcoma.
Carcinosarcomas can originate either from a pre-existing pleomorphic adenoma or may manifest de novo. These tumors are typically aggressive, with a clinical course marked by high-grade malignancy and a propensity for distant metastases, documented in approximately 54% of cases.
Chondrosarcoma is the most commonly observed sarcomatous element in carcinosarcomas, followed by fibrosarcoma, leiomyosarcoma, osteosarcoma, and liposarcoma. As for the carcinomatous elements, adenocarcinoma, undifferentiated carcinoma, and squamous cell carcinoma predominate. This case featured adenoid cystic carcinoma, characterized by predominant tubular and cribriform growth patterns, alongside focal solid growth patterns. Histomorphological analysis considered various differential diagnoses, including carcinoma ex-pleomorphic adenoma, a sarcomatoid variant of salivary duct carcinoma, and myoepithelial carcinoma. Immunohistochemistry played a pivotal role in confirming the diagnosis. The adenoid cystic carcinoma component exhibited positive staining for both ductal (CK7, CAM 5.2) and myoepithelial (p63, p40, cytokeratin, SMMH) markers, as well as CD117.
In contrast, the sarcomatous component tested negative for all epithelial markers, CD57, androgen receptors, and calponin. It displayed positivity for vimentin, with focal S-100 staining observed in the chondroid component. This immunohistochemical profile, coupled with the absence of a pre-existing parotid lesion and histological evidence of pleomorphic adenoma, supported a diagnosis of primary carcinosarcoma of the parotid gland. Fine needle aspiration cytology, although not extensively studied in carcinosarcomas, has been reported to yield suspicious or atypical results.
Conclusion
Magnetic Resonance Imaging (MRI) is the preferred imaging modality for carcinosarcomas, offering insights into the involvement of the deep lobe, facial nerve, and surrounding soft tissues. However, despite advancements in diagnostic and therapeutic modalities, carcinosarcomas carry a poor prognosis, with reported 2-year and 5-year survival rates of 68.1% and 37.2%, respectively. Median survival ranges from 10 months to 38 months, emphasizing the aggressive nature of these tumors. The treatment of choice involves radical parotidectomy followed by postoperative radiotherapy, which has been shown to significantly reduce recurrence rates compared to surgery alone. Distant metastases, predominantly hematogenous, remain a significant prognostic factor for poor survival outcomes.
Carcinosarcoma, a highly aggressive tumour, warrants aggressive treatment due to its poor prognosis. Further research is necessary to find out the origins of these tumours.
