Mediastinal gray zone lymphoma

Definition

A mediastinal lymphoma showing morphological and/or immunohistochemical features intermediate between those of mediastinal large B-cell lymphoma and nodular sclerosing Hodgkin lymphoma.

It is currently thought that the cell of origin of the malignant cells of Hodgkin lymphoma is a B-cell. An overlap with B-cell non-Hodgkin lymphoma is therefore not surprising.

Clinical features

Gray zone lymphomas, like cHL-NS and MLBCL occurs in young adults, but there is no a female predominance.

Histopathology

Composite cases show distinct areas of MLBCL and cHL-NS, but there are transitional areas resembling gray zone lymphoma.

Immunohistochemistry

Even those cases that are morphologically closer to MLBCL show an immunophenotype closer to classical Hodgkin lymphoma. Most gray zone lymphomas were positive for CD20.

	Reference 1	gray zone lymphomas		composite lymphomas		metachronous
	morphology	closer to MLBCL: n=10	closer to cHL: n=11	MLBCL	cHL	MLBCL	cHL
	CD10	1/5
	CD15	6/10	8/11	0/5	4/4	0/6	6/8
	CD20	7/10	11/11	6/6	1/5	6/6	1/8
	CD30	10/10	10/11	2/5	5/5	4/6	8/8
	CD45	2/3	3/6	4/4	0/3	5/5	2/6
	CD79a	3/4	7/9	2/2	0/2	2/3	0/3
	Pax-5	10/10	5/5	3/3	4/4	7/7	5/6
	BOB.1	8/9	5/5	4/4	1/3	6/6	1/6
	OCT.2	8/9	6/6	3/3	1/3	6/6	1/7
	PU.1	3/4	4/5	4/4	0/4	3/3	0/2
	MAL	3/4	4/5	3/3	1/2	2/2	1/3
	bcl-6	9/11 (weak and focal positivity)
	EBV	2/7 (both positive cases were of cHL morphology)

Prognosis

Relapses at abdominal or extranodal locations are common.

References

⁰ Tumours of the Lung, Pleura, Thymus and Heart. WHO Classification of Tumours. IARC Press 2004.

¹ Traverse-Glehen A, Pittaluga S, Gaulard P, et al. Mediastinal gray zone lymphoma: the missing link between classic Hodgkin's lymphoma and mediastinal large B-cell lymphoma. Am J Surg Pathol 2005; 29:1411-21

This page last revised 10.1.2006.

©SMUHT/PW Bishop