Special entities of lymphoma

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Burkitt's or Burkitt-like lymphomas: the particularly high proliferative capacity and aggressiveness of Burkitt's or Burkitt-like lymphomas is a problem even in HIV-negative patients. In this case, the CHOP regimen is insufficient (Trumper 2001). Although it is still unclear whether this is also true for HIV patients with Burkitt's lymphomas, many clinicians have in recent years tended to treat such patients more intensively.

A modified dose-adapted protocol of the German multicenter study group for adult acute lymphoblastic leukemia (GMALL) has mostly been used for the treatment of HIV-negative cases of Burkitt-NHL/B-ALL, and consists of four to six short, intensive 5-day polychemotherapy cycles, alternating A and B cycles. A cytoreductive pretreatment with cyclophosphamide and prednisone, each for 5 days, was given before the first cycle. During cycle A, fractionated doses of ifosphamide for 5 days, intermediate- or high-dose methotrexate 500-3,000 mg/m2, VM26, cytarabine (ara-C), vincristine, and dexamethasone are given. During cycle B, ara-C, VM26 and ifosphamide are replaced by doxorubicin and cyclophosphamide (Hoelzer 1996).

The preliminary data show better responses than with CHOP (Hoffmann 2004) and rates comparative to those of HIV-negative patients (Oriol 2003). However, the GMALL protocol is a very intensive chemotherapy, which cannot be administered on an outpatient basis. Strict monitoring of patients in hospital for several weeks is very important. Centers without experience in this intensive protocol should not administer it to HIV-infected patients.

As well as the GMALL protocol, a few other intensive therapies have been reported (Fieschi 2001, Cortes 2002, Lichtman 2003, Wang 2003). A significant problem with most of the currently available studies is that there is no control group. There is no randomized study. So, whether Burkitt's lymphoma in HIV patients has to actually always be treated intensively, can therefore not be definitely concluded yet.

Plasmablastic lymphomas: are a relatively new entity in HIV patients. Plasma-blastic lymphomas probably belong to the diffuse large-cell NHLs, but have a completely characteristic immunophenotype - markers for the B-cell antigen CD20 are negative, whereas the plasma-cell reactive antibodies VS38c and CD138 are positive (Brown 1998, Teruya-Feldstein 2004). The oral cavity is the site of involvement (Flaitz 2002, Gaidano 2002), although extra-oral manifestations do occur (Chetty 2003). There is a close association with HHV-8 (Cioc 2004). Like Burkitt's lymphoma, plasmablastic lymphomas have a very high rate of proliferation and are extremely aggressive. More recent data shows that the earlier very poor prognosis is markedly improved by HAART (Teruya-Feldstein 2004, Lester 2004). It is our opinion that patients should receive a more intensive treatment than CHOP-21. Primary effusion lymphoma (PEL): a further therapeutic problem is the relatively rare entity of the so-called primary effusion lymphoma which is also termed body cavity lymphoma (Carbone 1997, 2000). These lymphomas are often very difficult to diagnose histologically. A visible tumor mass is usually absent, so that malignant cells can only be found in body cavities (e.g. pleural, pericardial, peritoneal). There are histological similarities to immunoblastic and anaplastic cells with a non-B-, non-T phenotype. Every pleural or pericardial effusion occurring in an HIV patient and containing malignant cells, is suspicious of PEL. The involved pathologist should always be informed about this suspicion.

There is a characteristic close association with the herpes virus HHV-8, which can be detected in the malignant cells. Recently, a solitary variant has been reported, which is neither morphologically nor immunophenotypically distinguishable from the classical PEL types (Chadburn 2004). The response to CHOP is usually poor and poorer than that of centroblastic NHL (Simonelli 2003). Case studies with complete remission on HAART alone have been described (Boulanger 2001, Hocqueloux 2001). We have, however, seen two PEL patients who have also died of progression despite CHOP and HAART after only a few months.

Recently, a combined chemotherapy with high dose methotrexate has been reported, with which, in at least 3/7 patients, a lasting complete remission could be achieved - a notable achievement in view of the otherwise poor prognosis, and an approach that should be followed up (Boulanger 2003). On the other hand, there are reports in which even intensive treatment regimens were unsuccessful (Waddington 2004).

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