Primary effusion lymphoma, PEL

Definition

A neoplasm of large B-cells presenting as serous effusions without tumour masses. It is always associated with human herpes virus 8 (HHV-8, Kaposi sarcoma herpes virus, KSHV), usually in association with immunodeficiency secondary to HIV. Although often negative for B-cell antigens, the presence of immunoglobulin gene rearrangements is evidence that in most cases these lymphomas are of B cell derivation.

This may be considered a subtype of DLBCL. The majority of PELs occur exclusively as malignant effusions, but some patients secondarily develop solid tissue masses: others present with a mass and later develop an effusion. KSHV-positive solid lymphomas may be designated as extra-cavitary PELs. There is a case report of a nodal large T-cell lymphoma with HHV-8 infection and concomitent peritoneal effusion containing large lymphoid cells in an HIV-positive man3.

Synonyms

Epidemiology

Most patients are HIV+ homosexual males with a low CD4 count 2.

Clinical features

Usually only one body cavity (pleural, pericardial or peritoneal, rarely subarachnoid2) is involved. Other sites include the gastrointestinal tract, soft tissues and other extranodal sites, but their is usually neither lymphadenopathy nor organomegaly1. Patients may also have Kaposi sarcoma1. There is a rare association with multicentric Castleman disease1.

Histopathology

In cytospin preparations, the cells range from immunoblastic to plasmablastic to anaplastic. Some cells resemble Reed-Sternberg cells. Pleural biopsies show cells embedded within fibrin adherent to the pleural surface, in which specimens the cells appear more uniform.

Immunohistochemistry

		primary effusion lymphomas
	CD3	aberrant expression reported, 1/242
	CD5	1/242
	CD10	0/72
	CD15	0/172
	CD19	frequently negative, 0/182
	CD20	frequently negative, 1/292
	CD22	1/222
	CD30	positive, 18/232
	CD38	frequently positive, 11/162
	CD45	positive, 28/292
	CD79a	frequently negative, 0/92
	CD138	positive, 4/102
	cIg	frequently negative
	sIg	frequently negative
	kappa	0/272
	lambda	4/272
	bcl-6	0/82
	pax5	0/42
	NK	0/152
	HLA-DR	positive1, 16/202
	EMA	frequently positive, 16/202
	p53 (>20% of cells positive)	0/82
	HHV8	nuclear positivity
	KSHV LANA (ORF73)	9/92
	vIL6	9/92
	ORF59	0/22
	KSHV-associated K8.1	2/62
	LMP-1	negative
	EBER	10/132

There may be two phenotypic variants1:

IRF4+/CD138+, B-cell antigen-negative
IRF4+/CD138-, B-cell antigen-positive

Differential diagnosis

pyothorax associated with DLBCL, in which there is usually a pleural mass lesion; the cells are CD10-/CD20+/CD79a+/bcl-6-/MUM1+; they are EBV+ but HHV8-.

Prognosis

The median survival is less than six months1.

References

World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

1 Pileri, S.A., Dirnhofer, S., Went, P., Ascani, S., Sabattini, E., Marafioti, T., Tzankov, A., Leoncini, L., Falini, B. and Zinzani, P.L. Diffuse large B-cell lymphoma: one or more entities? Present controversies and possible tools for its subclassification. Histopathology 2002;41:482-509.

2 Chadburn, 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.

3 Coupland SE, Charlotte F, Mansour G, et al. HHV-8-associated T-cell lymphoma in a lymph node with concurrent peritoneal effusion in an HIV-positive man. Am J Surg Pathol 2005; 29:647-52

This page last revised 17.7.2005.