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	0/8	1/24
	CD5	0/3	1/24
	CD10	0/4	0/7
	CD15	0/6	0/17
	CD19	0/2	0/18
	CD20	1/8	1/29
	CD22	0/3	1/22
	CD30	5/7	18/23
	CD38	0/3	11/16
	CD45	5/7	28/29
	CD79a	1/5	0/9
	CD138	3/5	4/10
	kappa	0/8	0/27
	lambda	2/8	4/27
	bcl-6	0/3	0/8
	pax5	0/5	0/4
	NK	0/2	0/15
	HLA-DR	1/3	16/20
	EMA	5/7	16/20
	p53 (>20% of cells positive)	1/4	0/8
	KSHV LANA (ORF73)	8/8	9/9
	vIL6	4/5	9/9
	ORF59	0/3	0/2
	KSHV-associated K8.1	1/4	2/6
	EBER	7/7	10/13

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.

This page last revised 20.12.2004.

©SMUHT/PW Bishop