Lymphohistiocytoid malignant mesothelioma

Definition

This is a rare subtype, constituting less than 1% of all of malignant mesotheliomas3. It has traditionally been classified with sarcomatoid mesothelioma, but its prognosis is more in keeping with the usual epithelioid mesothelioma.

Epidemiology

Patients are usually elderly, with a mean of 70 years1. As for other mesotheliomas, men are more often afflicted than women. There is an association with prior asbestos exposure.

Clinical features

Presentation may be with chest pain, weight loss or fatigue.

Macroscopic appearances

There may be diffuse pleural thickening, pleural nodularity and a pleural effusion, lymphocytic or haemorrhagic.

Histopathology

There is a diffuse proliferation of large non-cohesive cells with eosinophilic cytoplasm, vesicular nuclei and prominent nucleoli, resembling histiocytes. Some may resemble Reed-Sternberg cells. There may be a malignant spindle cell component3. In one case, the atypical cells resembled ganglion cells3. In some cases, there is an infiltrate of plasma cells or eosinophils.

Immunohistochemistry

	Histiocytoid cells	Lymphoid cells
AE1/AE3	100%(of 22 cases)1, 3/4(only focally positive)4, 3/33
Calretinin	100%(of 22 cases)1, 3/4(only focally positive)4, 2/33
CK 5/6	46%(of 22 cases)1
HBME1	1/33
Thrombomodulin	1/33
EMA	52%(of 22 cases)1
CEA	0/41, 0/33
BerEP4	0/33
B72.3	0/41, 0/33
BG-8	0/33
Vimentin	2/33
CD15	0/41, 1/33
CD30	0%1
CD45	0%1, 0/33
CD68	0/33	4/4(positive in histiocytoid cells)4
S100	0%1
CD3	0/33	positive1, 4/41, 3/33
CD4		very few cells1
CD5	0/33	3/33
CD8		positive1, 4/41
CD20	0/33	scattered cells3
CD43	0/33	3/33
TDT	0/33	negative1, 0/33
LMP		negative1
EBER-1		negative1

Ultrastructure

Scattered cells have sinuous villi, intracytoplasmic lumina lined by microvilli and tonofilament bundles2,4.

Differential diagnosis

Hodgkin lymphoma
Non-Hodgkin lymphoma
Lymphoepithelial carcinoma
Sarcomatoid carcinoma of the lung
Thymoma: the malignant cells are usually positive for CD5. The lymphocytes are immature.
Reactive lymphoproliferative lesions, inflammatory pseudotumour
Ganglioneuroma3

Management

Patients have been managed by pleurodesis, chemotherapy and radiotherapy.

Prognosis

The median survival is 32 to 40 months1.

References

1 Galateau-Salle F, Attanoos R, Gibbs AR, et al. Lymphohistiocytoid variant of malignant mesothelioma of the pleura: a series of 22 cases. Am J Surg Pathol 2007; 31:711-6

2 Henderson DW, Attwood HD, Constance TJ, et al. Lymphohistiocytoid mesothelioma: a rare lymphomatoid variant of predominantly sarcomatoid mesothelioma. Ultrastruct Pathol 1988; 12:367-84

3 Khalidi HS, Medeiros LJ,Battifora H. Lymphohistiocytoid mesothelioma. An often misdiagnosed variant of sarcomatoid malignant mesothelioma. Am J Clin Pathol 2000; 113:649-54

4 Yao DX, Shia J, Erlandson RA, et al. Lymphohistiocytoid mesothelioma: a clinical, immunohistochemical and ultrastructural study of four cases and literature review. Ultrastruct Pathol 2004; 28:213-28

This page last revised 31.5.2007.