EBV-associated smooth muscle tumours

Definition

Smooth muscle tumours in the immunocompromised associated with Epstein-Barr virus infection. They have been variously categorized as leiomyomas, as smooth muscle tumours of uncertain malignant potential and as leiomyosarcomas.

Clinical features

These tumours occur in adults and children. There is a male predominance. The causes of immunosuppression in these patients include organ transplantation, AIDS and steroid therapy. The tumours occur at a wide range of sites including soft tissues,l liver, upper respiratory tract, lung, spleen, intestines, tonsils, bladder, adrenals, bone, thyroid, heart and central nervous system. Many patients develop multiple tumours, which appear to represent multiple infection events, rather than metastases, as evidenced by the variation in the long terminal repeat of the virus in each tumour.

Radiology

Macroscopic appearances

In some cases, pulmonary tumours may be multiple, minute and closely related to the media of blood vessels.

Histopathology

The tumour consists of smooth muscle cells with eosinophilic cytoplasm and blunt-ended nuclei. Nuclear atypia is limited. The mitotic rate varies, but is usually less than 3/10HPF. These tumours differ from conventional smooth muscle tumours:

there are masses of large primitive round cell with irregular nuclear outlines, superficially resembling atypical lymphoid cells.
There is an infiltrate of T-lymphocytes.

Immunohistochemistry

	SMA	29/291
	Desmin	14/261
	EBER	26/261
	CD3	T-cells only1
	CD20	negative1

Ultrastructure

Differential diagnosis

Sporadic leiomyosarcoma

Management

Prognosis

Death due to these tumours is uncommon, even when multiple.

References

1 Deyrup AT, Lee VK, Hill CE, et al. Epstein-Barr Virus-Associated Smooth Muscle Tumors Are Distinctive Mesenchymal Tumors Reflecting Multiple Infection Events: A Clinicopathologic and Molecular Analysis of 29 Tumors From 19 Patients. Am J Surg Pathol 2006; 30:75-82

This page last revised 28.1.2006.