Extra-cavitary PEL

Definition

In most cases, primary effusion lymphoma is devoid of a solid tissue component. However, a minority of cases secondarily develop a solid mass or present with a tissue mass and subsequently develop an effusion. Some cases appear to form part of this spectrum but never develop an effusion. These tumours are positive for Kaposi Sarcoma Herpes Virus.

Clinical features

There is a male predominance and a strong associated with HIV positivity.

Histopathology

The morphology is predominantly that of an immunoblastic lymphoma, with large nuclei showing a prominent central nucleolus. Lesser numbers of cells appear centroblastic or plasmacytoid. Some resemble Reed-Sternberg cells. There is a high mitotic rate and variable amounts of apoptotic debris. In one case, there was a prominent epithelioid histiocytic proliferation.

Immunohistochemistry with typical primary effusion lymphoma for comparison.

		extra-cavitary PELs	primary effusion lymphomas
	CD3	0/81	1/241
	CD5	0/31	1/241
	CD10	0/41	0/71
	CD15	0/61	0/171
	CD19	0/21	0/181
	CD20	1/81, 0/12	1/291
	CD22	0/31	1/221
	CD30	5/71	18/231
	CD38	0/31	11/161
	CD45	5/71, 1/12	28/291
	CD79a	1/51	0/91
	CD138	3/51, 1/1 (focal)2	4/101
	kappa	0/81	0/271
	lambda	2/81	4/271
	bcl-6	0/31, 0/12	0/81
	pax5	0/51, 0/12	0/41
	NK	0/21	0/151
	HLA-DR	1/31	16/201
	EMA	5/71	16/201
	p53 (>20% of cells positive)	1/41	0/81
	KSHV LANA (ORF73)	8/81, 1/12	9/91
	vIL6	4/51	9/91
	ORF59	0/31	0/21
	KSHV-associated K8.1	1/41	2/61
	EBER	7/71, 1/12	10/131

The expression of B-cell antigens appears to be more common in extra-cavitary PEL then in usual PEL.

Differential diagnosis

Other KSHV-associated lymphoproliferaitve conditons.

Prognosis

May be better than PEL, particularly with antiviral therapy.

References

¹Chadburn, A., E. Hyjek, et al. (2004). "KSHV-positive solid lymphomas represent an extra-cavitary variant of primary effusion lymphoma." Am J Surg Pathol 28(11): 1401-16.

² Dong HY, Scadden DT, de Leval L, et al. Plasmablastic lymphoma in HIV-positive patients: an aggressive Epstein-Barr virus-associated extramedullary plasmacytic neoplasm. Am J Surg Pathol 2005; 29:1633-41

This page last revised 30.7.2006.

©SMUHT/PW Bishop