Anaplastic large cell lymphoma presenting as a pleural effusion and mimicking primary effusion lymphoma. A report of 2 cases.
BACKGROUND
Systemic anaplastic large cell lymphoma (ALCL) is predominantly a nodal disease, but extranodal involvement can occur during the disease course or as the primary presentation. We report two rare cases of ALCL presenting with a pleural effusion, mimicking primary effusion lymphoma (PEL).


METHODS
Two patients, a 47-year-old woman and an 81-year-old man, presented with a pleural effusion for investigation. The pleural fluid contained abundant, large, lymphoid cells with marked nuclear atypia. These neoplastic cells strongly expressed CD30 and EMA and showed a T-cell phenotype (CD3+CD45RO+ for case 1 and CD4+ for case 2). Case 1, in addition, showed ALK1 expression. The tumor cells in both cases were negative for human herpes virus type 8 (HHV8) and Epstein-Barr virus (EBV). ALCL shows overlapping cytologic features with PEL, but the T-cell phenotype, ALK1 expression in case 1, lack of association with HHV8 and EBV, HIV seronegativity and subsequent discovery of nodal disease in case 2 were all in favor of ALCL over PEL.


CONCLUSIONS
In rare cases a pleural effusion is the presenting feature of ALCL, and distinction from PEL depends on correlation with clinical findings, detailed immunophenotyping and study of the status of HHV8 and EBV.
Chan
Alexander Chak-Lam
AC
Department of Pathology, Queen Elizabeth Hospital, 30 Gascoigne Road, Kowloon, Hong Kong. chancl@ha.org.hk
Chan
John Kwok-Cheung
JK
Yan
Kin Wing
KW
Kwong
Yok Lam
YL
D000368:Aged; D000369:Aged, 80 and over; D000077548:Anaplastic Lymphoma Kinase; D015703:Antigens, CD / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D016130:Immunophenotyping; D017728:Lymphoma, Large-Cell, Anaplastic / Q000175:diagnosis* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D016066:Pleural Effusion, Malignant / Q000175:diagnosis* / Q000201:enzymology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases
D015703:Antigens, CD; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases