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.

©SMUHT/PW Bishop