Diagnosis Of Malignant Mixed Tumor Research Articles

Salivary Gland-Type Tumors With Myoepithelial Differentiation Arising in Pulmonary Hamartoma

Reported is a hitherto unrecognized association of pulmonary hamartomas with salivary gland-type tumors showing myoepithelial differentiation, namely, a case of myoepithelioma arising in a otherwise classic hamartoma with cartilage predominance, and a case of malignant mixed tumor arising in a predominantly fibrous hamartoma resembling müllerian adenofibroma. The tumors occurred in middle-aged female patients of 35 and 44 years, respectively, and presented as 7 cm (treated with lobectomy) and 13 cm (treated with pneumonectomy) masses of the right upper lobe showing a short clinical history of cough, dyspnea, and wheezing. Both lesions did not present regional lymph node metastases after mediastinal lymphadenectomy. The myoepithelioma patient was well with no signs of recurrent disease at 6-month clinical control, but she was then lost to follow-up; the malignant mixed tumor patient is alive and well after 6 months since operation. Both tumors presented with morphologic and immunohistochemical features of myoepithelial cells, and we interpret them as being derived from a myoepithelial-like stromal cell population found within the hamartomatous areas, which is also consistently detected in classic pulmonary hamartoma. The lack of individual cell necrosis, mitotic activity, cell atypia, and pulmonary parenchyma infiltration supported a diagnosis of benign or unproven malignant potential tumor for the myoepithelioma, whereas the reverse held true for the other tumor in which the diagnosis of malignant mixed tumor of the lung was rendered. Their main importance of recognizing this association lies in separating these tumors histologically from other monophasic or biphasic tumors, either primary or secondary, such as pulmonary sarcomatoid carcinomas or true sarcomas, and metastatic salivary gland tumors, spindle cell carcinomas, melanomas, and soft tissue and visceral sarcomas.

Malignant mixed tumors arising in salivary glands.I. Carcinomas arising in benign mixed tumors: A clinicopathologic study

Forty-seven cases of malignant mixed tumor (MMT) arising in major and minor salivary glands are presented. By definition, all these lesions contained both a benign mixed tumor (BMT) as well as a malignant neoplasm, usually a poorly differentiated carcinoma. In some cases, the carcinoma developed in a previously untreated salivary gland mass which was known to have been present for many years, others evolved in a recurrent previously resected BMT and still others originated in a previously undetected BMT. Adverse prognostic factors included: carcinomatous involvement of the resection lines, perineural invasion, metastases in lymph nodes, and origin in a major salivary gland. Lesions arising in the palate had a better prognosis as compared to major salivary gland tumors. Some patients died of locally uncontrollable tumor and others because of metastatic disease. Local recurrences of MMT were seen frequently; 18 patients (38%) had a total of 32 local recurrences. Of patients followed five years or more, seven (35%) had died of tumor, 11 (55%) had no evidence of disease, and two (10%) had died of other causes. Prolonged follow-up is required because recurrences and death from tumor may be seen many years following the diagnosis of MMT. Recommendations for therapy are made. Criteria for differentiating MMT from recurrent BMT and from cylindromatous carcinoma are discussed.

Malignant mixed tumors of salivary gland origin.

One hundred and thirty-four salivary gland tumors originally diagnosed as malignant mixed tumor at the Armed Forces Institute of Pathology and the Medical College of South Carolina were analyzed. These were reclassified and only 25 were found to possess specific histopathologic criteria necessary for the diagnosis of malignant mixed tumor. Where possible, the clinical behavior, therapy, and prognosis were correlated with the histopathology. The malignant mixed tumor was found primarily in the parotid gland and was observed more frequently in men. The median age of patients with this tumor was 38 years (60% occurred prior to age 40). Pain and fixation of the tumor could not be correlated with malignancy. Sixty-four percent of these tumors presented as primary malignant mixed tumors. Histologically proven metastases were observed in 71% of the cases, with lung, lymph node, central nervous system, and bone the most frequent sites. Certain histopathologic features of the malignant mixed tumor can be correlated with eventual metastases. Although the pathogenesis of the malignant mixed tumor remains undetermined, the results of this study indicate that this neoplasm is malignant from the onset and does not develop from malignant transformation of a preexisting “benign” mixed tumor.