Plasmablastic Lymphoma in HIV-Positive Patients

Definition

Lymphoma with plasmablastic features and negative for CD20 in an HIV-positive patient. Some patients have bone marrow involvement and a paraprotein, suggesting an overlap with plasma cell myeloma.

Epidemiology

Most patients are male.

Clinical features

Patients are immunocompromised with reduced CD4 counts and most have a history of opportunistic infections or Kaposi's sarcoma. They may have a monoclonal serum gammopathy or a mixed polyclonal cryoglobulinemia. Patients present with extramedullary tumours, most often in the oral cavity but a range of other sites have been recorded.

Histopathology

Plasmablastic cells have basophilic cytoplasm and an eccentric round nucleus with clumped chromatin and a single prominent nucleolus. There is a continuum in the cytological appearance from plasmablastic to mature plasma cells. Multinucleate plasmablasts are common. Frequent mitoses and apoptotic cells are present.

Immunohistochemistry

	cIgH	5/111
	cIgL	3 kappa & 2 lambda / 131
	CD20	2/13(faint focal staining)1
	CD45	11/11
	CD138	10/101
	Pax-5	0/81
	bcl-6	0/101
	ALK-1	0/101
	EBV-EBER (in situ hybridisation)	11/111
	EBV-LMP-1 (in situ hybridisation)	0/51
	EBNA-2	negative1
	HHV8 (IHC)	0/1

Differential diagnosis

Plasmablastic plasma cell myeloma has a minority of plasmablasts. The cells are negative for EBV. Patients are usually older than 40 years.
Anaplastic plasma cell myeloma is composed of pleomorphic cells. The cells are negative for EBV. Patients are usually older than 40 years.
Immunoblastic lymphoma with plasmacytoid differentiation. The distinction may be arbitrary.
Burkitt's lymphoma with plasmacytoid differentiation. The tumour has a starry-sky pattern and a higher mitotic rate. The cells have multiple nucleoli, and are typically CD20+ BCL-6+.
ALK-1-positive large B-cell lymphoma shows a sinusoidal and nodular proliferation pattern. The cells are positive for ALK-1 but negative for EBV.
Primary effusion lymphomas are composed of larger, more pleomorphic cells, lack the uniform central nucleoli seen in plasmablastic lymphoma. In most cases there are effusions in body cavities without well-defined tissue masses. Cells are uniformly HHV8+.
Plasmablastic lymphoma associated with multicentric Castlemans disease. This is typically nodal or splenic and evolves against a background of Castlemans disease. The plasmablasts are CD20+ and are always IgM lambda restricted. They are typically HHV8+ but EBV-.

Prognosis

This is an aggressive lymphoma with a median survival of six months.

References

1 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.