- medium-sized cell
- mixed medium and large cell
- large cell
- Lennert's lymphoma / lymphoepithelioid lymphoma is a rare morphological variant of PTCL characterized by the presence of numerous clusters of epithelioid histiocytes without formation of discrete granulomas and the intervening atypical lymphocytes. At least some of the Lennert's lymphomas phenotypically correspond with cytotoxic T-cell lymphomasref1, ref2. Lymphoepitheloid T- cell was first described by Lennert (Habilitation thesis, 1952) and published (1968)ref, and later widely known as Lennert's lymphoma
- histologically lymphoepitheloid cell variant (Lennert lymphoma) shows diffuse or (more rarely) interfollicular infiltrates consisting predominantly of small cells with only slight nuclear irregularities. Numerous clusters of epitheloid histocytes are present. Clear cells or high endothelial venules are less frequent than in peripheral T- cell lymphomas of angioimmunoblastic or T-zone type. Few Reed-Sternberg-like cells, eosinophils and plasma cells can be seen
- immunophenotype : of 10 cases, CD3+4-8+ in 5 cases, CD3+4+8- in 4 cases, and CD3+4-8- in 1 case. TIA-1 was positive by immunohistochemical staining in 7 cases, whereas 4 cases were positive for granzyme B
Epidemiology : older individuals are generally affected
Symptoms & signs : splenomegaly and lymphadenopathy may be prominent features, with involvement of Waldayer's ring also observed in European casesref.
Laboratory examinations : bone marrow involvement is common
,
tuberculosis, sarcoidosis, abnormal immune response, peripheral T-cell
lymphoma, T-cell rich B-cell lymphoma, mixed cellularity Hodgkin's
disease,
nodular lymphocytic and histiocytic Hodgkin's lymphoma and lymphoepithelioma-like
carcinoma (Reich O, Pickel H, Purstner P: Exfoliative cytology of a lymphoepithelioma-like
carcinoma in a cervical smear. A case report. Acta Cytol 1999, 43:285-8
). Cytologically all the mentioned diseases can partly simulate lymphoepitheloid
lymphoma. In this case aggregates of epitheloid cell closely mimicked granuloma
in which conditions like TB should be considered. The monomorphic background
can easily rule out sarcoidosis or other reactive or immunologic process.
The cytology of NK/T-cell lymphomas show more pleomorphism with irregular
chromatin distribution and usually no epitheloid cellsref.
FNAC of lymph node involvement by high grade mycosis fungoides with monotonous
population of large and small cells can be misinterpreted. However mycosis
shows more anisocytosis with cerebriform convoluted nuclei against a background
of atypical lymphocytes, and plasma cellsref1,
ref2. Those
cases of T-cell rich B-cell lymphoma (TCRBL) which can show also many epitheloid
cells and predominance of mature small lymphocytes with few or absent atypical
large, immature lymphoid cells should be considered in differential diagnosisref.
However atypical large lymphoid cells are much more scarce in Lennert's
lymphoma and immunocytochemistry can clearly differentiate these cases,
which the large cells show B-cell marker and the small lymphocytes does
not have aberrant antigen expression. To our knowledge, literature on cytologic
findings of lymphoepitheloid lymphoma is sparseref.
Although final diagnosis of this variant of T cell lymphoma is confirmed
by immunohistochemical studies, cytologically the presence of monomorphic
lymphoid background with mild to absent atypia with closely intermingled
clusters of epitheloid histiocytes help for a correct preliminary working
diagnosis.
Therapy : response to chemotherapy is often poor (mean OS = 42 months)
