Coincidence of de novo T-lymphoblastic lymphoma and cutaneous gamma/delta peripheral T-cell lymphoma.

The coincidence of acute T-lymphoblastic leukemia/lymphoma, NOS (T-ALL/LBL), and peripheral T-cell lymphoma (PTCL) is unusual, and there have only been a few cases of their metachronous occurrence. In these cases, PTCLs emerged as recurrence after primary therapy for primary T-ALL, were the rare gamma/delta type, and uncommonly involved skin for T-ALL/LBL. We herein report the first case of de novo T-LBL that coincided with cutaneous gamma/delta PTCL before primary therapy. A 70-year-old man presented with systemic lymphadenopathy. Lymph node biopsy revealed a massive proliferation of lymphoblastoid cells; immunohistochemically, they were positive for TdT/CD1a/CD99, and cytoplasmic CD3ε, CD4, and CD8 and were negative for T-cell receptor (TCR) ßf-1. A few TCRδ-positive cells were intermingled. Atypically, TIA was focally positive, whereas granzyme/perforin was negative. Multiple papules and plaques emerged on the trunk before the initiation of treatment for T-LBL. Skin biopsy revealed a massive proliferation of medium-to-large atypical lymphoid cells that were TdT/CD1a-negative mature T-cells; they were negative for TCRßf1 and CD4, and positive for TCRδ, CD5, CD8, CD56, TIA, granzyme B, and perforin. A conventional PCR analysis of TCRG showed no identical clonal band between the two tumors. The skin lesion was diagnosed as cutaneous gamma/delta T-cell lymphoma. Whether the lesion was primary or a transformation of T-LBL was unclear. After treating with reduced hyper-CVAD/MA targeting T-LBL, molecular complete remission was achieved. When an uncommon cutaneous lesion emerges in the course of T-ALL/LBL, both need to be evaluated pathologically and genetically, whether de novo or recurrent, assuming the possibility of coincident gamma/delta PTCL.

[Thoracic SMARCA4-deficient undifferentiated tumor resembling malignant lymphoma].

We present a case of thoracic SMARCA4-deficient undifferentiated tumor that needed to be differentiated from malignant lymphoma owing to multiple lymph node swelling and marrow involvement. A 52-year-old man developed multiple lymphadenopathies along with anorexia, general fatigue, fever, and sweating 2 months prior to admission. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan revealed a mass lesion on the right upper lung, generalized lymph node swelling, and bone metastasis, indicating the presence of suspicious lung cancer; therefore, he was referred to our hospital. Malignant lymphoma was suspected at the time of admission because of elevated levels of lactate dehydrogenase (11,977 U/l) and soluble interleukin 2 receptor (2,152 U/ml) as well as marrow infiltration of large abnormal cells. On day 11, the patient died from rapid respiratory failure. Histological and immunohistochemical features of the pleural effusion cell block led to the diagnosis of thoracic SMARCA4-deficient undifferentiated tumor. Thoracic SMARCA4-deficient undifferentiated tumor was recently introduced in the 2021 World Health Organization classification of lung tumors, with most patients being young adults with a history of heavy smoking and poor prognosis. Because of the multiple lymph node swelling and marrow involvement, this undifferentiated tumor should be distinguished from malignant lymphoma.

Bendamustine-induced rash is associated with a favorable prognosis in patients with indolent B-cell lymphoma.

Bendamustine is now recognized as a key drug for indolent B-cell lymphoma (iBCL), mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL). Skin toxicity associated with bendamustine is one of the characteristic adverse effects. We retrospectively examined the relationship between bendamustine-associated drug rashes and disease prognosis of iBCL and MCL at our institution. Between January 2011 and August 2019, 65 patients (39 men and 26 women, median age 68, range 41-84 years) were treated with bendamustine alone (n=11, 120 mg/m2 on days 1 and 2) or a combination of rituximab and bendamustine (n=54, 90 mg/m2 on days 1 and 2). Of these patients, 47 had follicular lymphoma (FL), 10 had MCL and 8 had other iBCLs. Drug rash occurred in 27 (41.5%). Eight cases (29.6%) were grade 1, 5 (18.5%) were grade 2 and 14 (51.9%) were grade 3. The onset was in the first course in 17 (63.0%), 2nd course in 5 (18.5%), 3rd course in 2 (7.4%), 4th course in 1 (3.7%) and 5th course in 2 (7.4%). No treatment was administered in 1 case (3.7%), topical steroid was applied in 10 (37.0%), antiallergic drug was administered in 2 (7.4%), topical steroid and antiallergic drug were administered in 5 (18.5%), and oral and topical steroid and antiallergic drug were administered in 9 (33.3%). The 3-year progression-free survival (PFS) and overall survival (OS) in patients with rash development were 80.0% and 85.5%, respectively, and those in patients without development were 36.4% and 54.0%, respectively (p=0.009 and 0.02, respectively). By multivariate analysis, the development of rash was associated with a better PFS and a diagnosis of iBCL was associated with a better OS. This study revealed that bendamustine-induced rash is associated with a favorable prognosis among patients with iBCL.

Paravertebral extramedullary hematopoiesis in a case of myelodysplastic syndrome with ring sideroblasts and an SF3B1 mutation.

We present the case of a 56-year-old male patient with paravertebral extramedullary hematopoiesis (EMH) secondary to myelodysplastic syndrome with ring sideroblasts and multilineage dysplasia. In a routine health checkup over 5 years prior, he presented with asymptomatic mild anemia and a posterior mediastinal mass. Pathological and cytomorphological findings of the resected paravertebral mass were similar to those of his bone marrow specimen, and included cellularity with erythroid hyperplasia, multilineage dysplastic changes, and the presence of ring sideroblasts. A concordant SF3B1 mutation was detected in both bone marrow and paravertebral mass samples, suggesting that the EMH cells were derived from the bone marrow.

Genetic features of B-cell lymphoblastic lymphoma with TCF3-PBX1.

BACKGROUND: Lymphoblastic lymphoma (LBL) and acute lymphoblastic leukemia (ALL) are categorized as the same entity under precursor lymphoid neoplasms in the World Health Organization classification. However, compared to B-cell ALL, the molecular genetic makeup of B-cell LBL remains to be understood, mainly due to its rarity. We performed whole exome sequencing (WES) on seven patients with TCF3-PBX1-positive B-cell LBL. METHODS: WES was performed using DNA extracted from tumor specimens and paired blood samples at remission for six patients, and tumor-only analysis was performed for one patient whose remission sample was not available. For one patient, a relapsed sample was also analyzed. RESULTS: KMT2D variants and 6q LOH were found as recurrent alterations. Somatic variants of KMT2D were identified in three of the seven patients. Of note, the two patients with heterozygous nonsense variant of KMT2D were at stage III, without bone marrow infiltration. 6q LOH was also identified in two others, out of the seven patients. The common 6q deleted region of the two patients ranged from 6q12 to 6q16.3. Both patients had bone marrow infiltration. Analysis of recurrent case also revealed that the relapsed clone might be derived from a minor clone of the bone marrow at diagnosis. CONCLUSION: In this study, through WES for seven patients with TCF3-PBX1-positive B-LBL, we identified KMT2D mutations and 6q LOH as recurrent alterations. In order to elucidate the relationship between these recurrent alterations and disease specificity or outcomes, further studies comparing with TCF3-PBX1-positive B-ALL are required.

Prognostic impact of peripheral blood Wilms' tumour 1 mRNA expression levels in response to azacytidine in MDS: A single-centre analysis.

To determine the impact of peripheral blood (PB) Wilms' tumour 1 (WT-1) mRNA levels in patients with primary myelodysplastic syndromes (MDS), we analysed the relationships between several clinical variables at the time of diagnosis and the haematological response of patients treated with azacytidine. We observed overall responses in 20 (63%) patients; there were no significant differences in clinical variables, including bone marrow blast counts, IPSS scores and IPSS-R risk scores, between responders and non-responders. The responders' PB WT-1 mRNA levels were significantly lower than those of non-responders (P = 0.03). PB WT-1 mRNA expression could be a marker for predicting the response to azacytidine in patients with de novo MDS.

Indolent T-cell lymphoproliferative disorder of the stomach successfully treated by radiotherapy.

Successful treatment of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract (ITLPDGI) by chemotherapy is rare and watchful waiting is often performed for asymptomatic patients. We report a case of ITLPDGI successfully treated by involved field radiotherapy (IFRT). The patient presented with slow ITLPDGI localised to the stomach with mild symptoms. IFRT (30 Gy/20f) was administered, after which endoscopy revealed resolution of lesions and blood vessel appearance, and absence of proliferating abnormal lymphocytes was confirmed by biopsy. The patient remains lymphoma-free 1 year post-treatment. Although long-term follow-up and additional cases are essential for the evaluation of IFRT as a treatment option for localised ITLPDGL, complete remission after relatively low-dose IFRT is promising, particularly as this has been rarely achieved by chemotherapy.

Ultra-high sensitivity HBsAg assay can diagnose HBV reactivation following rituximab-based therapy in patients with lymphoma.

BACKGROUND & AIMS: HBV reactivation is a risk in patients receiving anti-CD20 antibodies for the treatment of lymphoma. The purpose of this post hoc analysis was to evaluate the efficacy of an ultra-high sensitivity HBsAg assay to guide preemptive antiviral treatment in patients with lymphoma and resolved HBV infections using prospectively stored samples from an HBV DNA monitoring study. METHODS: HBV reactivation (defined as HBV DNA levels of ≥11 IU/ml) was confirmed in 22 of 252 patients. A conventional HBsAg assay (ARCHITECT, cut-off value: 0.05 IU/ml) and an ultra-high sensitivity HBsAg assay employing a semi-automated immune complex transfer chemiluminescence enzyme technique (ICT-CLEIA, cut-off value: 0.0005 IU/ml) were performed at baseline, at confirmed HBV reactivation and monitored after HBV reactivation. RESULTS: Baseline HBsAg was detected using ICT-CLEIA in 4 patients; in all of whom precore mutants with high replication capacity were reactivated. Of the 6 patients with HBV DNA detected below the level of quantification at baseline, 5 showed HBV reactivation and 3 of the 5 had precore mutations. Sensitivity for detection by ARCHITECT and ICT-CLEIA HBsAg assays at HBV reactivation or the next sampling after HBV reactivation was 18.2% (4 of 22) and 77.3% (17 of 22), respectively. Of the 5 patients undetectable by ICT-CLEIA, HBV reactivation resolved spontaneously in 2 patients. All 6 patients reactivated with precore mutations including preS deletion could be diagnosed by ICT-CLEIA HBsAg assay at an early stage of HBV reactivation. Multivariate analysis showed that an anti-HBs titer of less than 10 mIU/ml, HBV DNA detected but below the level of quantification, and HBsAg detected by ICT-CLEIA at baseline were independent risk factors for HBV reactivation (adjusted hazard ratios, 15.4, 31.2 and 8.7, respectively; p <0.05). CONCLUSIONS: A novel ICT-CLEIA HBsAg assay is an alternative method to diagnose HBV reactivation. CLINICAL TRIAL NUMBER: UMIN000001299. LAY SUMMARY: Hepatitis B virus can be reactivated in lymphoma patients receiving anti-CD20 antibodies such as rituximab. Currently, reactivation requires the monitoring of HBV DNA, but monitoring of the surface antigen (HBsAg) could provide a relatively inexpensive, quick and easy alternative. We assessed the performance of an ultra-high sensitivity HBsAg assay and showed that it could be effective for the diagnosis and monitoring of HBV reactivation.

Peripheral T-cell lymphoma with gastrointestinal involvement and indolent T-lymphoproliferative disorders of the gastrointestinal tract.

The 2017 WHO classification includes a new provisional entity of indolent T-lymphoproliferative disorders of the gastrointestinal tract (ITLPD-GIT). We investigated GI involvement of peripheral T-cell lymphoma (PTCL). Eighty-two patients were diagnosed with PTCL during 2007-2017. Eleven patients (13 %) had histologically-confirmed GI tract involvement {3 monomorphic epitheliotropic intestinal lymphoma (MEITL), 3 extranodal NK-/T-cell lymphoma nasal type (ENKL), 2 PTCL, not otherwise specified, 1 adult T-cell leukemia-lymphoma, 2 ITLPD-GIT}. Three patients each had lesions in the small intestine and multiple lesions, two each in the stomach and colon, and one in the duodenum. Six of the 11 patients remained alive. No perforation/stenosis was observed after chemo-radiotherapy, although one patient with ENKL developed gastric bleeding during chemotherapy. One patient with ITLPD-GIT (CD4-/CD8+/Ki67Low) with a colonic lesion showing diffuse edema and multiple aphtha by endoscope and diarrhea, initially diagnosed with MEITL, had active but stable disease after various chemotherapies for 1 year and no therapy for the next 5 years. Another patient with ITLPD-GIT (CD4+/CD8+/Ki67Low) with a localized gastric lesion and slight epigastralgia was in remission for 1 year after radiation. In conclusion, about 10 % of PTCLs were complicated by GI tract lesions and most had a poor prognosis. ITLPD-GIT should be considered as a differential diagnosis based on histology and clinical course. Local complications after chemo/radiotherapy in PTCL with GI involvement were not frequent.

A case series of adult T-cell leukemia-lymphoma, associated with human T-cell leukemia virus type-1, at a single center in a non-viral-endemic metropolitan area.

We examined 13 patients with adult T-cell leukemia-lymphoma (ATL) diagnosed between 2007 and 2018 at a single center in a metropolitan area non-endemic for human T-cell leukemia virus type I (HTLV-1). The median age of the patients (eight male, five female) was 65 years (range, 48-83). The time from onset of symptoms to referral to our center was relatively short (median, 2 months; range, 1-9 months). Upon referral, all patients were suspected to have lymphoma, five were examined for soluble IL-2 receptor and two were examined for anti-HTLV-1 antibody. In ten of the 13 (77%), the patient themselves or their relatives were born in Kyushu. The birth places of the remaining three patients were unknown. Three patients (23%) had family histories of lymphoma. They all exhibited aggressive ATL (five acute, eight lymphoma type); however, the disease status was generally stable, with relatively stable performance status and low scores for prognostic indices. After combination chemotherapy, eight (62%) achieved remission. However, long-term remission was achieved in only one patient with localized lymphoma-type ATL and one young patient after allogeneic hematopoietic stem cell transplantation. In conclusion, at a center in a metropolitan and HTLV-1 non-endemic area in Japan, patients with ATL were relatively young and mainly presented with aggressive subtypes. At initial referral to our center, all 13 patients were suspected of having lymphoma but only two of having ATL. For centers in similar areas of Japan, prompt diagnosis and appropriate treatment of ATL patients will become increasingly necessary following the recent migration of HTLV-1 carriers to non-endemic areas.

Monitoring of Hepatitis B Virus (HBV) DNA and Risk of HBV Reactivation in B-Cell Lymphoma: A Prospective Observational Study.

BACKGROUND: There is no standard management of reactivation of hepatitis B virus (HBV) infection in HBV-resolved patients without hepatitis B surface antigen (HBsAg), but with antibodies against hepatitis B core antigen and/or antibodies against HBsAg (anti-HBs). METHODS: We conducted a prospective observational study to evaluate the occurrence of HBV reactivation by serial monthly monitoring of HBV DNA and to establish preemptive therapy guided by this monitoring in B-cell non-Hodgkin lymphoma (B-NHL) treated with rituximab plus corticosteroid-containing chemotherapy (R-steroid-chemo). The primary endpoint was the incidence of HBV reactivation defined as quantifiable HBV DNA levels of ≥ 11 IU/mL. RESULTS: With a median HBV DNA follow-up of 562 days, HBV reactivation was observed in 21 of the 269 analyzed patients. The incidence of HBV reactivation at 1.5 years was 8.3% (95% confidence interval, 5.5-12.4). No hepatitis due to HBV reactivation was observed in patients who received antiviral treatment when HBV DNA levels were between 11 and 432 IU/mL. An anti-HBs titer of <10 mIU/mL and detectable HBV DNA remaining below the level of quantification at baseline were independent risk factors for HBV reactivation (hazard ratio, 20.6 and 56.2, respectively; P < .001). Even in 6 patients with a rapid increase of HBV due to mutations, the monthly HBV DNA monitoring was effective at preventing HBV-related hepatitis. CONCLUSIONS: Monthly monitoring of HBV DNA is useful for preventing HBV reactivation-related hepatitis among B-NHL patients with resolved HBV infection following R-steroid-chemo (UMIN000001299).

Hematologic improvements in a myelodysplastic syndromes with myelofibrosis (MDS-F) patient treated with azacitidine.

Myelodysplastic syndromes with myelofibrosis (MDS-F) is a poor prognostic hematopoietic disorder. Azacitidine was shown to prolong survival of high-risk MDS patients. However, the effects of azacitidine on MDS-F have yet to be elucidated. Azacitidine was administered to a 74-year-old man with MDS-F at a dose of 75 mg/m(2)/daily subcutaneously for 7 days every 28 days. Hematologic improvements were observed according to the International Working Group 2006 criteria after 8 cycles of the azacitidine treatment, and complete remission was achieved after 14 cycles. The grade of myelofibrosis was also improved. The therapeutic activity of azacitidine was confirmed in our MDS-F patient.

Prospective analysis of hepatitis B virus reactivation in patients with diffuse large B-cell lymphoma after rituximab combination chemotherapy.

PURPOSE: Recently, there have been reports of hepatitis B virus (HBV) reactivation after rituximab combination chemotherapy in hepatitis B surface antigen (HBsAg) -negative patients with B-cell lymphoma. In this prospective study, the frequency of and risk factors for HBV reactivation in patients who were receiving rituximab chemotherapy were examined. PATIENTS AND METHODS: A total of 314 HBsAg-negative patients with diffuse large B-cell lymphoma were treated with rituximab chemotherapy. Antibody to hepatitis B surface antigen (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) tests were performed in all patients. In patients who were positive for anti-HBs and/or anti-HBc, serum HBV-DNA was measured. RESULTS: Of the 314 patients, 51 (16.2%) were HBV carriers. HBV reactivation occurred during or after rituximab chemotherapy in six patients (12%). All six patients who developed HBV reactivation were anti-HBc positive, and three of them were also anti-HBs positive. In these six patients, the pretreatment anti-HBs titer was low. Entecavir administration was started when serum HBV DNA became positive, and serum HBV-DNA became negative within 1 to 3 weeks. Rituximab chemotherapy was then continued. Risk factors for HBV reactivation were being male and having a low anti-HBs titer. CONCLUSION: HBV reactivation occurred in some patients who had been anti-HBs negative or had a low anti-HBs level. In addition, HBV reactivation occurred at an early stage of rituximab chemotherapy, but rituximab chemotherapy could be continued after entecavir administration reduced the serum HBV-DNA level. Entecavir (BMS 200495) prophylaxis was not performed when rituximab chemotherapy was started, and it was thought that entecavir could be started when serum HBV-DNA increased.

A case of giardiasis expressing severe systemic symptoms and marked hypereosinophilia.

An 88-year-old Japanese woman was referred to our hospital due to a one-month history of face edema, aphagia, shortness of breath, and skin rush over almost her entire skin. She had no abdominal symptoms. Her peripheral blood count showed a white blood cell (WBC) count of 27.1x10(9)/L with 82.1% eosinophils. Serum non-specific Immunoglobulin E was within a normal range. Soluble interleukin-2 receptor was elevated to 4200U/mL. At first, her eosinophil count was so high that we suspected she had an eosinophilic leukemia or hypereosinophilic syndrome. After admission, cysts of Giardia duodenalis (G. duodenalis) were detected in the patient's feces by microscopic analysis, then she was diagnosed with giardiasis, and 750mg per day of metronidazole was administered for seven days. Her WBC count decreased to 6.0x10(9)/L with 10% eosinophils, and her systemic symptoms improved. At that time her serum IL-5 was within a normal range. A few months later, the patient again complained of skin rush, and G. duodenalis was once again found in her feces. Her serum IL-5 was elevated to 751pg/mL. Metronidazole was administered for two weeks, and her eosinophil count decreased. G. duodenalis is a protozoan parasite, and it is one of the most common waterborne transmission gastrointestinal parasites in the world. G. duodenalis rarely causes hypereosinophilia. To our knowledge, this is the first case report of giardiasis with extreme hypereosinophilia and severe systemic symptoms.

[Marfan syndrome complicated with CD5+ CD10+ diffuse large B-cell lymphoma].

Marfan syndrome (MFS) is caused by mutations in the gene encoding fibrillin. A 35-year-old man with MFS visited a local physician because of a sore throat. His left tonsil gradually became swollen and he was referred to our department. Histopathological examination of tonsil biopsy specimens showed diffuse proliferation of lymphoma cells with large nuclei. The tumor cells showed CD5+, CD10+, CD20+, BCL-6+, and MUM-1-. Based on these findings, the patient was diagnosed with CD5+ CD10+ diffuse large B-cell lymphoma (DLBCL). Chemotherapy combined with rituximab was administered and complete response was achieved. CD5+ DLBCL comprises approximately 5 approximately 10% of DLBCLs. In addition, CD5+ CD10+ DLBCL comprises about 5% of CD5+ DLBCLs. There may be a relationship between MFS and B-cell lymphoma because mutations in the gene encoding the receptor of transforming growth factor-beta (TGF-beta) have been implicated in the pathogenesis of MFS and downregulation of TGF-beta receptor expression has been described in the pathology of B-cell lymphoma.

Multicentre phase II study of CyclOBEAP plus rituximab in patients with diffuse large B-cell lymphoma.

The R-CHOP regimen has been found to improve the outcome of diffuse large B-cell lymphoma (DLBCL). However, it does not provide a satisfactory treatment outcome in the high-risk group. We previously administered the CyclOBEAP regimen to patients with DLBCL, and reported its safety and efficacy. The R-CyclOBEAP regimen was administered over a total period of 12 weeks, and rituximab 375 mg/m(2) was given every 2 weeks. There were 101 eligible patients. CR was achieved in 96 patients (95%). The 5-year overall survival (OS) rate was 85% and progression-free survival (PFS) rate was 76%. When the patients were divided according to the IPI, the 5-year OS and PFS rates did not significantly differ among the risk groups. The 5-year PFS of the germinal centre B-cell group was 80% and that of the non-GCB group was 74% (NS). Univariate analysis showed that the presence of B symptoms, extranodal lesions >or=2, and sIL-2R were significant poor prognostic factors. Grade 4 neutropenia was observed in 91 patients and thrombocytopenia in 9 patients. The addition of rituximab to CyclOBEAP therapy may enhance the effect of CyclOBEAP therapy for DLBCL.

Primary cutaneous anaplastic large-cell lymphoma presenting with hemophagocytic syndrome: a case report and review of the literature.

Primary cutaneous anaplastic large-cell lymphoma (C-ALCL) is a rare entity of lymphoma. We report a case of C-ALCL presenting with hemophagocytic syndrome and skin lesion with giant ulcer. Histopathological examination of the skin biopsy specimens showed non-epidermotropic infiltrates with cohesive sheets of large tumor cells. The tumor cells showed CD4-, CD8+, CD30+, CD56-, ALK-, TIA-1+, and granzyme B+. C-ALCL is generally a disorder that progresses slowly and has a good prognosis. Manifestation of a giant ulcer and hemophagocytic syndrome, such as in the present case, is rare.

Alveolar rhabdomyosarcoma mimicking nasal lymphoma at the initial presentation.

Rhabdomyosarcoma is exceedingly rare in adults. A 62-year-old woman was referred to our hospital because of general pain. Computed tomography revealed a solid tumor in the right nasal cavity. Histopathological examination showed solid proliferation of atypical small round cells, having cytologic features reminiscent of lymphomas, and lacking the fibrovascular stroma. The cells were CD56(+), desmin(+), vimentin(+), HHF35(+), myogenin(+) and MyoD1(+). The patient was positive for the PAX3-FKHR fusion gene. The patient was diagnosed as having alveolar rhabdomyosarcoma. We conclude that rhabdomyosarcoma should be included in the differential diagnoses of CD56(+) small round cell tumor, and immunohistochemical and cytogenetic studies should be performed.

Primary pulmonary plasmacytoma involving bilateral lungs and marked hypergammaglobulinemia: differentiation from extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue.

A 71-year-old woman was referred to our hospital because of hyperproteinemia and serum M-protein (IgG-lambda type). Chest computed tomographic (CT) scan revealed a tumor in each lung and transbronchial lung biopsy was performed. Histopathological examination showed monotonous medullary proliferation of morphologically mature plasma cells. These cells were cIgG+, cIg-lambda+, CD 20+, CD 79 a+, CD 138+, cIg-kappa-, and CD3-. Since there were very few non-neoplastic plasma cells and small lymphocytes in addition to the absence of reactive lymph follicles and fibrosis, the patient was diagnosed as having plasmacytoma. There was no proliferation of plasma cells in the bone marrow. Thus, the lesion was finally characterized as primary pulmonary plasmacytoma. Treatment with melphalan/prednisolone resulted in considerable decrease in the serum IgG level and regression of the pulmonary tumors. The effectiveness of the chemotherapy could confirm our diagnosis, although MALT-type lymphoma with plasmacytic differentiation cannot be completely ruled out.