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mediastinal leiomyoma

Sunday 18 March 2018

Definition: A mediastinal leiomyoma is a leiomyoma arising in the mediastinum.

To qualify as a primary mediastinal leiomyoma, tumours should arise from the somatic soft tissue of the mediastinum, whilst esophageal and large vessel primaries should be excluded.

If these criteria are applied, primary mediastinal leiomyoma is very rare with approximately 20 reported cases in the literature in 2015.

Mediastinal leiomyoma is twice as common in females as in males and is mainly seen in the posterior mediastinum of older adults (age range 23–75 years; median age 50 years).

These tumours may remain asymptomatic, or patients may complain of dyspnea or chest pain. The tumours may grow to a large size (up to 1,600 g).

The morphology of mediastinal leiomyoma is similar to its counterparts elsewhere in the body and is defined as a neoplasm resembling normal smooth muscle cells and devoid of pleomorphism and necrosis and with a very low mitotic rate (@<@1 mitoses/50 HPF).

Immunohistochemical stains will show positivity for smooth muscle actin and desmin in the majority of cases.

Surgical removal is curative, and in the reports with follow-up, no recurrences or deaths due to tumour were described.

The main differential diagnosis of leiomyoma is leiomyosarcoma, which is distinguished by increased mitotic activity, pleomorphism and necrosis.

Open references

- Mesenchymal tumours of the mediastinum—part II. 2015. doi : 10.1007/s00428-015-1832-6