Primary mediastinal B-cell lymphoma with sclerosis: an aggressive tumor with distinctive clinical and pathologic features.
OBJECTIVE
To evaluate the clinical features of presentation, the morphologic and immunohistochemical pattern, the modality of spread, and the response to current treatments of patients with primary mediastinal B-cell lymphoma, a recently documented subtype of non-Hodgkin's lymphoma (NHL).


METHODS
Thirty consecutive patients (14 males, 16 females; median age, 26 years) with primary mediastinal B-cell lymphoma with sclerosis were studied.


RESULTS
The clinical aspects were largely homogeneous: 93% presented with chest symptoms of a rapidly enlarging mass of the anterior mediastinum; the tumor was bulky in 73%, and superior vena cava syndrome (SVCS) was present in 57%. Also, patients without SVCS symptoms showed subclinical venacaval compression at computed tomographic (CT) scan, for a total incidence of caval obstruction of 80%. Intrathoracic extension to adjacent organs was seen in 47% of patients. Despite its invasive behavior, only four patients showed extrathoracic spread at diagnosis. In 23 cases, the tumor presented with morphologic features that resembled follicular center-cell lymphomas. In seven, the neoplastic population was composed mainly of centrocyte-like cells with abundant clear cytoplasm not referable to any known B-cell lymphoma subtype. All cases showed huge sclerosis. Of 29 patients assessable for response, 16 (55%) achieved a complete response (CR): five of 14 (36%) treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), and 11 of 15 (73%) treated with methotrexate plus leucovarin, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) or etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (VACOP-B) (P = .047). We could identify no clinical, biologic, or histopathologic features significantly correlated with response. After chemotherapy, 14 of 16 remitters received consolidation radiotherapy to the mediastinum. At 3 years, the actuarial survival rate is 38% for all cases and 72% for remitters. None of the 13 patients who did not achieve CR responded to salvage treatments.


CONCLUSIONS
This study shows that primary mediastinal B-cell lymphoma with sclerosis is a distinctive subtype of NHL with unique clinicopathologic aspects and aggressive behavior. Prompt recognition and aggressive treatment may provide long survival in a good proportion of cases. However, a subset of patients is extremely refractory to first- and second-line treatment. Conventional prognostic factors seem inadequate to identify these very-poor-risk cases.
Lazzarino
M
M
Institute of Hematology, University of Pavia, Policlinico S. Matteo, Italy.
Orlandi
E
E
Paulli
M
M
Boveri
E
E
Morra
E
E
Brusamolino
E
E
Kindl
S
S
Rosso
R
R
Astori
C
C
Buonanno
M C
MC
D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016393:Lymphoma, B-Cell / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology*; D008297:Male; D008479:Mediastinal Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology*; D012598:Sclerosis; D016019:Survival Analysis; D016896:Treatment Outcome