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A 65-year-old woman presented with fever and abnormal behavior. Magnetic resonance imaging showed swelling of the left medial temporal lobe and an intracranial extra-axial occipital tumor. While her neurological symptoms improved after the administration of corticosteroid therapy under the suspicion of autoimmune encephalitis, the occipital tumor unexpectedly shrank, and the diagnosis of a solitary plasmacytoma was confirmed by biopsy. Additional examinations revealed elevated anti-glutamate receptor antibodies in the cerebrospinal fluid. The patient was diagnosed with autoimmune encephalitis concurrent with an intracranial solitary plasmacytoma. Central nervous system involvement can be considered a neurological complication in patients with a solitary plasmacytoma.

Introduction: Multiple myeloma (MM) with pulmonary extramedullary disease is rare and usually associated with poor prognosis, and no data on daratumumab-based regimens have been reported yet., Case Presentation: Here, a 64-year-old man with pulmonary plasmacytoma received daratumumab-based regimens and has achieved a very good partial response with lung mass disappearance and overall survival of 16 months. He did not receive autologous stem cell transplantation because of several comorbidities, such as severe drug-induced neuropathy and JAK2-mutated myeloproliferative neoplasm with marked splenomegaly., Conclusions: We showed the efficacy of daratumumab in combination with targeted therapies for the treatment of pulmonary MM., (© 2024 The Author(s). Cancer Reports published by Wiley Periodicals LLC.)

Histologic diagnosis of less well-differentiated cases of canine extramedullary plasmacytomas (CEMPs) may require immunohistochemical confirmation to discriminate these tumors from other round cells tumors including lymphoma, cutaneous histiocytoma, and amelanotic melanomas. CEMPs are characterized by widespread immunoreactivity for multiple myeloma 1 (MUM1) antigen and λ light chains, while the melanocytic marker melan-A has been reported to yield negative results. Here, 33 randomly selected CEMPs, 20 melanocytomas, and 20 malignant melanomas were immunohistochemically tested for MUM1, melan-A, and PNL2. In addition, CEMPs were examined for PAX5, E-cadherin, CD3, CD18, CD20, S100, as well as λ and κ light chain immunoreactivity. All CEMPs were characterized by labeling for MUM1 and λ light chain, as well as variable immunopositivity for the remaining antibodies. Notably, 13 cases of CEMPs (39.4%) exhibited immunolabeling for melan-A. Melanocytic tumors immunolabeled for melan-A (40/40; 100%) and PNL2 (34/40; 85%). An unexpected cytoplasmic immunoreactivity for MUM1 was observed in 2 melanocytic tumors. Summarized, MUM1 or melan-A immunomarkers alone are not sufficient to differentiate between CEMPs and amelanotic melanomas and should be part of a larger immunopanel including λ light chain, CD20, and PNL2., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: In order to better understand the condition and provide the groundwork for early detection and treatment of plasmacytomas, it is important to examine the clinical characteristics, therapeutic options, and effectiveness of plasmacytomas that are initially identified with head and neck symptoms. Methods: Retrospective analysis, evaluation, and discussion of the clinical data of 7 patients with plasmacytoma initially diagnosed with head and neck symptoms and admitted to the Affiliated Hospital of Qingdao University during the period of June 2013 to November 2022 was done in combination with pertinent literature. Results: All seven patients were diagnosed with plasmacytoma by histopathology, with lesions located in the nasopharyngeal oropharynx in 4 cases, nasal sinuses in 2 cases, and ventricular zone in 1 case. Clinical manifestations and imaging were atypical, with localized manifestations, of which 2 cases were accompanied by multiple skeletal lesions throughout the body, and 4 cases had lymph node metastasis. Surgery was preferred for all patients, and individualized treatment was recommended after surgery. Of the 7 patients, 3 patients underwent surgery and chemotherapy, 2 patients underwent surgery and radiotherapy and chemotherapy, 1 patient underwent surgery and radiotherapy, and 1 case was treated with surgery only. The follow-up period was 3-60 months, with a 100% follow-up rate. 5 cases were alive and 2 cases died of multiple myeloma after 4-5 years Conclusion: Plasmacytomas first diagnosed with head and neck symptoms are rare, and extramedullary plasmacytomas have a better prognosis, while more advanced multiple myeloma has a poorer prognosis; Therefore, enhancing the quality of survival as well as the duration of survival for patients with plasmacytomas requires early diagnosis and individualized treatment., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)

Competing Interests: The authors report no conflicts of interest.

A plasmacytoma is a single, isolated tumour of abnormal plasma cells. It can develop within the bone, known as solitary plasmacytoma of bone, or outside the bone, referred to as extraosseous (extramedullary) plasmacytoma, without spreading to other parts of the body. Plasmacytoma, an uncommon presentation in the posterior mediastinum, usually arises as solitary or multiple lesions in bone or soft tissues. The standard treatment involves definitive radiotherapy, potentially curative for extramedullary cases. The prognosis varies, being more favourable without concurrent multiple myeloma and worsening with high-risk cytogenetics. The case involves a male in his early 80s with an extensive medical history presenting with difficulty swallowing and dyspnoea. The diagnosis revealed a rare posterior mediastinal plasmacytoma associated with multiple myeloma, emphasising the importance of prompt diagnosis and treatment., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Orbital plasmacytoma is a rare plasma cell tumor that may arise as an aggressive form of extramedullary multiple myeloma. Treatment modalities include surgical excision, radiation, and chemotherapy. Chimeric antigen receptor T cell therapy is currently reserved for refractory disease. The authors present a case of a 69-year-old woman with an extensive orbital plasmacytoma refractory to multimodal therapy who was treated with idecabtagene vicleucel chimeric antigen receptor T cell therapy. Four days after infusion, the patient exhibited grade 1 cytokine release syndrome, which resolved with tocilizumab. The orbital plasmacytoma significantly decreased in size 1 month after treatment and demonstrated complete serological response and sustained tumor burden reduction at 10-month follow-up. This case highlights the efficacy of chimeric antigen receptor T cell therapy for refractory orbital plasmacytoma and calls attention to potential inflammatory toxicities., Competing Interests: The authors have no financial or conflicts of interest to disclose., (Copyright © 2024 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.)

Background: Plasmacytoma of the skull base is a rare manifestation of plasma cell neoplasm with only a few cases documented in literature involving young adults. Plasmacytoma can be an isolated solitary lesion or a secondary manifestation of multiple myeloma (MM). In this study, we report the clinical and radiological characteristics, management, and outcomes of patients under the age of 40 who presented with skull base plasmacytoma and associated neurological manifestations. Additionally, we share our experience in treating a rare case of skull base plasmacytoma diagnosed during pregnancy, in which the patient exhibited a favorable response to myeloma treatment initiated after delivery., Case Series: Four patients were identified, comprising one pregnant female and three male patients, with a median age of 36 years (range 33-37 years). The main presenting symptoms were headache, dizziness, and cranial nerve palsy. All patients received underwent systemic myeloma therapy and radiotherapy with three patients also underwent autologous stem cell transplantation (ASCT). Notably, all patients achieved complete remission., Conclusion: Skull base plasmacytoma represents a rare manifestation of plasma cell neoplasms, underscoring the importance of considering it in the differential diagnosis of skull base lesions to ensure early intervention and avoid potential serious complications. Throughout our series, the cornerstone of therapy involved radiotherapy, systemic myeloma therapy, and ASCT, all of which elicited a favorable response in every case., (© 2024 The Author(s). Cancer Reports published by Wiley Periodicals LLC.)

We report a rare case of spontaneous regression (SR) in an elderly untreated patient with multiple solitary plasmacytoma (MSP). Diagnosis of MSP was confirmed through surgical resection of the left nasal cavity mass and subsequent biopsy of the right humerus. The patient was considered ineligible for chemotherapy due to poor performance status. At 3-month post-diagnosis, the patient's condition worsened with deteriorating bone lesions and emergence of a new serum monoclonal protein. However, these clinical findings completely disappeared at 6 months, and positron emission tomography-computed tomography at 1 year confirmed complete metabolic remission. Notably, peripheral blood lymphocyte counts were inversely correlated with tumor progression and remission. Pathological re-evaluation of the initial biopsy specimens revealed programmed cell death protein 1 (PD-1) expression in tumor-infiltrating CD8 + T cells. In addition, tumor cells were infected with Epstein-Barr virus (EBV) but were negative for programmed cell death ligand 1 (PD-L1) expression, which is the most potent immune escape mechanism in tumor cells. While the mechanism underlying SR remains unclear, our findings suggest that host immune response as well as EBV infection may contribute to SR. Further studies are needed to elucidate the clinicopathologic mechanisms of tumor regression in plasma cell neoplasms., (© 2024. Japanese Society of Hematology.)

Multiple myeloma associated with extramedullary plasmacytoma at initial presentation is rare. We describe a case of a man in his 30s who initially presented with symptoms of spinal cord compression. Further imaging revealed a mediastinal tumour, with a biopsy confirming plasmacytoma. Immunofixation revealed IgA lambda paraprotein. Bone marrow biopsy demonstrated atypical T-cell cytotoxic proliferation and trilineage hypoplasia. The patient was diagnosed with extramedullary plasmacytoma with active IgA multiple myeloma. The patient received mediastinal radiation to the tumour, followed by anti-myeloma therapy. This diagnosis is critical as managing a solitary plasmacytoma drastically differs from an extramedullary plasmacytoma with active multiple myeloma., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Extramedullary plasmacytoma (EMP) is a rare plasma cell malignancy, especially when the tumor originates in skeletal muscle. Plasmablastic plasmacytoma is an anaplastic round cell tumor with highly malignancy and poor prognosis. To date, there have been no reports on the transformation of skeletal muscle EMP into plasmablastic plasmacytoma. Therefore, the diagnosis, treatment, and prognosis of cases of this pathologic transformation are unclear., Case Presentation: This article reports a case of an elderly male patient who presented with a painless mass in the right calf and was diagnosed with EMP by puncture pathology. Complete remission was obtained after sequential chemoradiotherapy. 6 months later, another puncture was performed due to plasmablastic plasmacytoma multiple distant metastases, and the pathology showed that EMP was transformed to plasmablastic plasmacytoma. Despite aggressive antitumor therapy, the disease continued to deteriorate, and the patient ultimately died of respiratory failure., Conclusion: The transformation of EMP into plasmablastic plasmacytoma is very rare, and its diagnosis and treatment require the participation of both experienced pathologists and clinicians. We report this case in order to raise clinicians' awareness of the diagnosis and treatment of EMP and its transformation to plasmablastic plasmacytoma, and to avoid misdiagnosis and underdiagnosis., (© 2024. The Author(s).)

Extramedullary plasmacytoma (EMP) is a special type of malignant plasmacytosis, which is complex and heterogeneous. Most EMP patients have poor prognosis and lack a stratified prognostic system or ideal treatment strategy supported by evidence-based medical evidence, which cannot meet clinical needs. In order to improve the understanding of this disease entity, Plasma Cell Disease Group, Chinese Society of Hematology, Chinese Medical Association and Chinese Myeloma Committee-Chinese Hematology Association developed the "Chinese Expert Consensus on the diagnosis and treatment of extramedullary plasmacytoma", which aims to standardize the clinical diagnosis and treatment of EMP and ultimately improve the overall survival of patients with plasmacytoma.

Plasmacytoma is defined as a plasma cell neoplasm forming a solitary osseous or extramedullary tumor without evidence of myeloma or organ damage related to a plasma cell neoplasm. Epstein-Barr virus (EBV) is associated with various B-cell neoplasms, particularly in patients with immune dysregulation; however, plasmacytoma is typically negative for EBV. Here, a case of EBV-positive sternal plasmacytoma in an immunocompetent female is presented. A 76-year-old female with no immunodeficiency presented with a tumor on the anterior thoracic wall. Imaging analysis revealed a 6.3 cm-sized tumor at the manubrium, and a needle biopsy was performed. The tumor in the bone was composed of a diffuse proliferation of plasmacytes with eccentric nuclei and a perinuclear halo. By immunohistochemistry and in situ hybridization, tumor cells were CD20-, CD3-, CD138+, κ+, λ-, EBER+, and the Ki67-labeling index was approximately 20%. Subsequent studies identified IgG κ monoclonal protein in serum but no evidence of plasma cell neoplasm-related organ damage, such as hypercalcemia, anemia, or renal dysfunction. No plasma cell neoplasm was detected in the bone marrow in the morphological and flowcytometric studies. Accordingly, the diagnosis was EBV-positive plasmacytoma. The patient was treated with local radiation therapy and achieved complete remission. EBV-positive plasmacytoma is rare in immunocompetent patients and should be carefully distinguished from plasmablastic lymphoma, another EBV-positive neoplasm with a plasma cell phenotype and an aggressive clinical course. This case also raises an important question: "when to perform EBER in situ hybridization in diagnosing plasma cell neoplasm?", which prompts further large case-series studies.

Plasmacytoma is a rare plasma cell dyscrasia that grows in bones or soft tissues such as the pharynx. Soft tissue plasmacytomas are rare, and a higher burden has been reported in the upper aero-digestive tract, often manifesting as hoarseness, dysphagia, or odynophagia. Due to their rarity, extramedullary plasmacytomas (EMPs) have unknown prognostic factors, and guidelines for optimal management are still lacking. However, radiation therapy and surgery have been used with positive outcomes. Herein, we describe a unique case of plasmacytoma of the pharyngeal tissue in a male patient with a history of HIV disease. The patient completed 28 sessions of radiation therapy, resulting in an improvement in his throat pain and hoarseness. Given the patient's age and lack of traditional risk factors for head and neck cancers, his hoarseness and odynophagia proved to be a diagnostic conundrum. Although infrequent, soft tissue plasmacytomas should be considered in the differential diagnosis of head and neck tumors., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Solitary plasmacytoma is a rare, localized malignancy. Bone localizations are the most common. Extramedullary plasmacytomas are much rarer. They are most often in the upper respiratory tract and can be complicated by amyloidosis. Here is an original report of a mediastinal extramedullary plasmacytoma revealed by type AA renal amyloidosis., Case Presentation: We present the case of a 52-year-old patient with mediastinal extramedullary plasmocytoma diagnosed by renal failure due to type AA renal amyloidosis. Treatment was based on surgery with chemotherapy based on prednisone and melphalan. The patient presented end-stage renal failure that required hemodialysis at discharge., Conclusion: Extramedullary plasmacytoma is a rare tumour that may be associated with amyloidosis, usually type AL. To our knowledge, its association with AA amyloidosis has not been reported in the literature. Treatment is based on surgery combined with radiotherapy or chemotherapy.

Competing Interests: The authors declare no conflicts of interest.

Primary extraosseous plasmacytoma (PEP) is a rare and localized form of plasmacytoma that is not well understood. This study aimed to investigate the clinical features and prognostic factors associated with PEP. Using the Surveillance, Epidemiology, and End Results (SEER) database, a total of 1044 patients diagnosed with PEP between 2000 and 2019 were identified. The average age was 60.3 ± 15.2 years, with 64.3% being male (male: female = 1.8:1) and 53.8% being over 60-year old. The survival outcome of patients with PEP depends on several factors including age, race, marital status, and treatment options such as chemotherapy, radiotherapy, and surgery, which were also identified as independent predictors of overall survival for PEP. Patients who were younger, Asian or Pacific Islander, American Indian or Native American, and received radiotherapy or surgery had a more favorable prognosis, while those who underwent chemotherapy had poorer outcomes.

BACKGROUND AL amyloidomas are solitary, localized, tumor-like deposits of immunoglobulin light-chain-derived amyloid fibrils in the absence of systemic amyloidosis. A rare entity, they have been described in various anatomical sites, typically in spatial association with a sparse lymphoplasmacytic infiltrate, ultimately corresponding to a clonal, malignant, lymphomatous disorder accounting for the amyloidogenic activity. Most frequently, the amyloidoma-associated hematological disorder corresponds to either a solitary plasmacytoma or an extranodal marginal zone lymphoma of MALT. Much rarer is the association with lymphoplasmacytic lymphoma, which by itself is usually a bone marrow-bound disorder with systemic burden. The almost anecdotic combination of an amyloidoma and a localized lymphoplasmacytic lymphoma deserves attention, as it entails a thorough diagnostic workup to exclude systemic involvement and a proportionate therapeutic approach to avoid overtreatment. A review of the literature provides an insight on pathogenesis and prognosis, and can assist both pathologists and clinicians in establishing optimal patient management strategies. CASE REPORT We herein report the incidental finding of a subcutaneous amyloidoma caused by a spatially related, similarly localized lymphoplasmacytic lymphoma diagnosed in a 54-year-old female patient with no other disease localizations and a complete remission following 2 subsequent surgical excisions. CONCLUSIONS Whatever the specific combination of an amyloidoma and the related hematological neoplasm, a multidisciplinary collaboration and a comprehensive clinical-pathological staging are warranted to exclude systemic involvement and identify patients with localized diseases who would benefit from local active treatment and close follow-up.

Objectives: Extraosseous plasmacytoma (EOP) is a rare plasma cell neoplasm that tends to convert to plasma cell myeloma (PCM) in about 11% to 35% of cases. It has a predilection for the upper respiratory tract, prototypically affecting the nasal cavity and paranasal sinuses. Contemporary first-line treatment is radiotherapy, with more recent studies showing an added benefit of combining radiation with surgery. In this cohort study, we aimed to examine clinical presentation, treatment, and prognosis for all patients nationwide from 1980 through 2017. Furthermore, we determined the size and extension of tumors, investigating the rate at which minimally invasive surgery would have been possible., Methods: Patients were found in the national pathology registry, and all biopsies were collected for pathology review by a hematopathologist. We performed survival statistics for overall survival (OS), progression-free survival (PFS), and the cumulative incidence of conversion to PCM., Results: Twenty-three patients were included. The median age was 65, and patients were primarily men (78%). Tumors were located in either the nasal cavity (57%), maxillary sinus (39%), or sphenoid sinus (4%). In most cases, the tumor was <5 cm (65%) without extension to adjacent structures (60%). The national incidence was 0.02/100,000 person-years, the median symptom duration until diagnosis was 5 months, and none of the patients presented with contiguous spread to regional lymph nodes. Stand-alone radiotherapy was the predominant treatment (61%). In the entire cohort, one patient died from the initial disease, and six patients died from either relapse of EOP or PCM. The 5-year OS, PFS, and conversion rate to PCM were 78%, 56%, and 23%, respectively., Conclusion: SN-EOP responds well to radiotherapy, but relapse and conversion to PCM were not uncommon and entailed a poor prognosis. Most tumors were endoscopically resectable and non-invasive, making the majority of tumors suitable for surgery as an addition to radiation.

Introduction: Plasmacytoma, a localized tumor of monoclonal plasma cells without any clinical, radiological or physical evidence of plasma cell neoplasm (PCN), is a rare entity that accounts for 1% of PCN. Immunoglobulin M (IgM) extramedullary plasmacytoma of mediastinal region has never been reported and is a diagnostic challenge considering other differential diagnoses., Case Presentation: We present the case of a 51-year-old African-American female with progressively increasing cough, dyspnea, and dysphagia for 6 months with a computed tomography (CT) scan revealing a subcarinal mass. The histopathological analysis of the mass reveals a diagnosis of lymphoma with plasma cell differentiation, with a differential of lymphoplasmacytic lymphoma and plasma cell neoplasm. The lymphoma panel via next-generation sequencing (NGS) and a myeloma-targeted fluorescent in situ hybridization (FISH) panel confirmed the diagnosis of IgM extramedullary plasmacytoma, an entity of rare occurrence. Treatment with radiation led to complete regression of the plasmacytoma with normal blood work-up., Conclusions: This report describes the challenges of diagnosing IgM extramedullary plasmactyoma. Our case report highlights the importance of cytogenetics and NGS in establishing a correct diagnosis that indeed has prognostic and therapeutic implications., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Study Design: Retrospective analysis., Objective: This study aimed to establish nomograms for predicting overall survival (OS) and cancer-specific survival (CSS) in patients with solitary plasmacytoma of the spine (SPS)., Summary of Background Data: SPS is a rare type of malignant spinal tumor. A systematic study of prognostic factors associated with survival can provide guidance to clinicians and patients. Consideration of other causes of death (OCOD) in CSS will improve clinical practicability., Methods: A total of 1078 patients extracted from the SEER database between 2000 and 2018 were analyzed. Patients were grouped into training and testing data sets (7:3). Factors associated with OS and CSS were identified by Cox regression and competing risk regression, respectively, for the establishment of nomograms on a training data set. The testing data set was used for the external validation of the performance of the nomograms using calibration curves, Brier's scores, C-indexes, time-dependent receiver operating characteristic curves, and decision curve analysis (DCA)., Results: Age and grade were identified as factors associated with both OS and CSS, along with marital status, radiation for OS, and chemotherapy for CSS. Heart disease, cerebrovascular disease, and diabetes mellitus were found to be the 3 most common causes of OCOD. The nomograms showed satisfactory agreement on calibration plots for both training and testing data sets. Integrated Brier score, C-index, and overall area under the curve on the testing data set were 0.162/0.717/0.789 and 0.173/0.709/0.756 for OS and CSS, respectively. DCA curves showed a good clinical net benefit. Nomogram-based web tools were developed for clinical application., Conclusion: This study provides evidence for risk factors and prognostication of survival in SPS patients. The novel nomograms and web-based tools we developed demonstrated good performance and might serve as accessory tools for clinical decision-making and SPS management., Level of Evidence: 3., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

BACKGROUND The differential diagnosis for a parotid mass is broad, including infectious, autoimmune, and neoplastic etiologies. In people with HIV, regardless of viral suppression or immune status, neoplastic causes are more common. This report describes the evaluation of a woman with a large parotid mass, with an ultimate diagnosis of multiple myeloma with extramedullary plasmacytoma. CASE REPORT A 51-year-old woman with HIV infection presented with headache, weight loss, and right facial mass that was present for 5 years but more rapidly enlarging in the prior year. CD4 count was 234 cells/mL, and HIV RNA was 10 810 copies/mL. Physical examination was significant for a large deforming right-sided facial mass, decreased sensation in the V1 and V2 distributions, and right-sided ophthalmoplegia and ptosis. MRI and PET/CT scan confirmed a metabolically active large parotid mass with extension into the cavernous sinus. An IgG kappa monoclonal spike was present on serum protein electrophoresis. Incisional biopsy of the facial mass showed atypical lymphoid cells with plasmablastic and plasmacytic morphology with a high mitotic rate and proliferation index. She was diagnosed with R-ISS stage II IgG kappa multiple myeloma with extramedullary plasmacytoma, and initiated on chemotherapy, radiation, and antiretroviral therapy. CONCLUSIONS A rapidly enlarging parotid mass should prompt timely evaluation and biopsy for definitive diagnosis, particularly in immunocompromised patients, including people with HIV. Extramedullary plasmacytomas have a more aggressive disease process in people with HIV and are associated with high-risk multiple myeloma and progression, as seen in this patient.

Aims: Epstein-Barr virus (EBV) is causally associated with many hematolymphoid malignancies. This laboratory-based study aimed to establish the prevalence of EBV in plasma cell neoplasms in a large South African cohort and to determine whether there is any correlation between EBV-positivity and human immunodeficiency virus (HIV) status in patients with plasma cell neoplasms, including plasma cell myeloma and plasmacytoma (solitary plasmacytoma of bone and extraosseous plasmacytoma)., Methods: This single-institution retrospective study included all patients with a histopathologic diagnosis of plasma cell neoplasm between 2003 and 2020. EBV-expression in the plasma cell neoplasms was assessed by EBV-encoded RNA (EBER) in situ hybridization (ISH) and correlated with HIV status. HIV status was determined by retrieving prior serologic results. Formalin-fixed paraffin-embedded tissue from HIV-unknown patients underwent HIV-1 p24 antibody testing., Results: Sixteen of 89 plasma cell neoplasms (18%) were EBV-positive. There was a significant correlation between EBV and HIV infection in plasma cell neoplasms, with 6/10 tumors from HIV positive patients showing EBV-positivity in tumor cells. The EBV-positive cohort was significantly younger than the EBV-negative group., Conclusion: EBV-positivity in plasma cell neoplasms in this study is higher than previously reported. The significant occurrence of EBV in plasma cell neoplasms from HIV-positive patients suggests a co-carcinogenic relationship between the two viruses.

Extramedullary involvement in multiple myeloma is uncommon. It can present as a plasma cell mass in the soft tissue surrounding the bony structures through direct extension or in various other organs via hematogenous spread. Here, we report a case of paraskeletal plasmacytoma that manifested as a chest wall mass in a 60-year-old man.

Rationale: Plasmacytoma is a rare plasma cell dyscrasia that grows within the axial skeleton or soft tissue structures as solitary or multiple masses. The primary types are solitary plasmacytoma, including solitary bone plasmacytoma (SBP) and solitary extramedullary plasmacytoma, and multiple solitary plasmacytomas. SBP is characterized by localized proliferation of monoclonal plasma cells and is rare. However, SBP with chronic osteomyelitis is even rarer., Patient Concerns: A 47-year-old man previously diagnosed with chronic osteomyelitis presented with repeated discharge and ulceration in the front of his right tibia., Diagnosis, Interventions and Outcomes: Lower extremity magnetic resonance imaging (MRI) and computed tomography (CT) examinations showed dead bone formation and surrounding inflammatory edema. Thus, the patient underwent dead bone excision and fenestration of the bone marrow cavity. The histopathologic examination results indicated plasmacytoma. Therefore, we administered radiotherapy with satisfactory results., Lessons: Physicians should pay close attention to chronic osteomyelitis because it may be accompanied by plasmacytoma. Postoperative pathological and immunohistochemical examinations are crucial, and surgical resection of the lesion and local radiotherapy are effective treatment methods., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

A 36-year-old man developed polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (POEMS) syndrome after conversion from solitary plasmacytoma of bone to multiple myeloma. Twenty-four days following the neurological onset, he lost his independent walking ability. The level of serum vascular endothelial growth factor (VEGF) at diagnosis was 5,250 pg/mL. Three months after initiating treatment, he regained his independent walking ability in line with a reduction in the elevated serum VEGF level. Due to their genomic instability gained during conversion, myeloma cells may overproduce humoral factors and cytokines, possibly contributing to the development of neuropathy as well as the production of VEGF.

Tracheal tumors are rare, accounting for 0.1% of all malignancies. Squamous cell carcinoma and adenoid cystic carcinoma are the two most prevalent tracheal cancers. Less than 20 cases of extramedullary plasmacytoma in the trachea and main bronchus have ever been documented in the literature, making it extremely uncommon. Although the origin of these lesions is unclear, viral pathogenesis and persistent inflammation are thought to be the main causes. Clinically, these individuals exhibit vague symptoms such as stridor, a persistent cough, dyspnea, or wheezing, making a correct diagnosis difficult., (© 2023 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.)

Nodular amyloidoma in the lungs is a rare entity, also the occurrence of extramedullary plasmacytoma (EMP) in the lungs is rare. To have concomitant EMP and amyloidoma presented as a single lung mass is even rarer. There was only one similar case reported in the abstract form previously. Our case did not respond to many novel chemotherapy agents, suggesting that this combination of amyloidoma and plasmacytoma belonged to a poor prognosis entity, requiring different treatment modalities, such as early bone marrow transplantation or CART (chimeric antigen receptors T) therapy.

Plasma cell neoplasms including multiple myeloma (MM) and related terminally differentiated B-cell neoplasms are characterized by secretion of monoclonal immunoglobulin and stepwise development from a preneoplastic clonal B and/or plasma cell proliferation called monoclonal gammopathy of undetermined significance (MGUS). Diagnosis of these disorders requires integration of clinical, laboratory, and morphological features. While their classification mostly remains unchanged compared to the revised 2016 WHO classification and the 2014 International Myeloma Working Group consensus, some changes in criteria and terminology were proposed in the 2022 International Consensus Classification (ICC) of mature lymphoid neoplasms. MGUS of IgM type is now divided into IgM MGUS of plasma cell type, precursor to the rare IgM MM and characterized by MM-type cytogenetics, lack of clonal B-cells and absence of MYD88 mutation, and IgM MGUS, NOS including the remaining cases. Primary cold agglutinin disease is recognized as a new entity. MM is now formally subdivided into cytogenetic groups, recognizing the importance of genetics for clinical features and prognosis. MM with recurrent genetic abnormalities includes MM with CCND family translocations, MM with MAF family translocations, MM with NSD2 translocation, and MM with hyperdiploidy, with the remaining cases classified as MM, NOS. For diagnosis of localized plasma cell tumors, solitary plasmacytoma of bone, and primary extraosseous plasmacytoma, the importance of excluding minimal bone marrow infiltration by flow cytometry is emphasized. Primary systemic amyloidosis is renamed immunoglobulin light chain amyloidosis (AL), and a localized AL amyloidosis is recognized as a distinct entity. This review summarizes the updates on plasma cell neoplasms and related entities proposed in the 2022 ICC. KEY POINTS: • Lymphoplasmacytic lymphoma can be diagnosed with lymphoplasmacytic aggregates in trephine biopsies < 10% of cellularity and evidence of clonal B-cells and plasma cells. • IgM MGUS is subdivided into a plasma cell type and a not otherwise specified (NOS) type. • Primary cold agglutinin disease is recognized as a new entity. • The term "multiple myeloma" replaces the term "plasma cell myeloma" used in the 2016 WHO classification. • Multiple myeloma is subdivided into 4 mutually exclusive cytogenetic groups and MM NOS. • Minimal bone marrow infiltration detected by flow cytometry is of major prognostic importance for solitary plasmacytoma of bone and to a lesser extent for primary extraosseous plasmacytoma. • Localized IG light chain amyloidosis is recognized as a separate entity, distinct from systemic immunoglobulin light chain (AL) amyloidosis., (© 2022. The Author(s).)

This review provides current information on myeloma-related disorders, a group of plasma cell or immunoglobulin (Ig) secreting neoplasms including multiple myeloma, extramedullary plasmacytoma (both cutaneous and noncutaneous variants), solitary osseous plasmacytoma, Waldenström macroglobulinemia/lymphoplasmacytic lymphoma, Ig-secretory B-cell lymphoma, plasma cell leukemia, and monoclonal gammopathy of undetermined significance. The diagnostic procedures commonly used to characterize myeloma-related disorders, including cytopathology, histopathology, polymerase chain reaction for antigen receptor rearrangement, flow cytometry, and electrophoretic techniques are outlined and discussed., Competing Interests: Disclosure The author declares no conflicts of interest., (Copyright © 2022 Elsevier Inc. All rights reserved.)

We herein report a rare case of distal chronic inflammatory demyelinating polyneuropathy (CIDP) following coronavirus disease 2019 (COVID-19) vaccination. A 39-year-old woman with a solitary plasmacytoma developed general weakness 7 days after receiving the second dose of the Pfizer-BioNTech COVID-19 vaccine, which had progressed for 3 months. A neurological examination revealed limb weakness with areflexia. Serological tests identified the presence of IgG antibodies against anti-GM1 and anti-GM2 gangliosides. Comprehensive evaluations met the criteria of distal CIDP. Intravenous immunoglobulin, intravenous methylprednisolone, oral prednisolone, and plasma exchange were administered, and she gradually improved. Physicians should be aware of CIDP as a rare complication of COVID-19 vaccination.

Introduction: Plasma cell neoplasms are exceptionally rare in the pediatric population; the demographic characteristics and the clinical outcomes of plasma cell neoplasms in this population are currently poorly understood. The aim of this study was to provide a comprehensive analysis of pediatric plasma cell neoplasms, based on the United-States Surveillance, Epidemiology, and End Results (SEER) program registries., Materials and Methods: All pediatric patients (aged less than 20 years) diagnosed with a malignant plasma cell neoplasm were retrieved from the SEER Program database (18 registries), collecting patient records between 2000 and 2018. The plasma cell neoplasm type, sex, age at diagnosis, year of diagnosis, race and origin, primary disease site, follow-up duration, and vital status at the last known contact were retrieved and analyzed., Results: The age-adjusted incidence rate of plasma cell neoplasms for 1,000,000 person-years was 0.06 for the pediatric population (compared with 90.6 for the adult population). The types of pediatric plasma cell neoplasms predominantly consisted of plasmacytomas, with 11 solitary extraosseous plasmacytoma (42.3%) and 7 solitary bone plasmacytoma (26.9%), while plasma cell myelomas represented only a minority of the neoplasms (8 patients; 30.8%). Most plasmacytomas were localized in the head and neck region. Hispanic patients represented 50% of the pediatric plasma cell neoplasm cases (but only 11.1% of adult cases, P < .01). Female-to-Male ratio was 1.36. Five-year overall survival rates were 88.2% (95% confidence interval [95% CI]: 74.2%-100%) for pediatric plasmacytoma and 36.5% (95% CI: 12.4%-100%) for pediatric plasma cell myeloma (P = .013)., Conclusion: This first population-based study of pediatric plasma cell neoplasms underlines the rarity of this entity and demonstrates its unique characteristics, including the significant predominance of plasmacytomas, of female patients, and of patients from hispanic origin, and the poor clinical outcomes of pediatric plasma cell myeloma patients., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Extramedullary (extraosseous) plasmacytoma (EMP) of the small intestine is a rare plasma cell neoplasm (PCN) that presents with abdominal pain, nausea, vomiting, etc. We describe 2 cases of EMP of the small intestine that presented with ileus., Methods: A 78-year-old woman and 68-year-old man visited our clinic with complaints of abdominal discomfort and obstruction. Abdominal computed tomography (CT) revealed a thickened lesion with multiple enlarged mesenteric lymph nodes (LNs) in the ileum and duodenum. The female patient underwent segmental resection in the ileum. The male patient underwent Whipple's operation in the duodenum., Results: Histopathological examination and immunohistochemical staining of resected specimens from the 2 patients confirmed a PCN. In the surgical specimens of 2 cases, immunoglobulin heavy-chain rearrangement was confirmed by polymerase chain reaction amplification, but no Epstein-Barr virus (EBV)-infected cells were found by EBV-in situ hybridization. Bone marrow aspirate and trephine biopsies were negative for the type of PCN. Bone marrow cytogenetics and fluorescence in situ hybridization revealed no abnormalities. Serum β2-microglobulin levels were within normal limits. Additionally, none of the patients showed an M-spike in serum or urine protein electrophoresis. Therefore, the patients were diagnosed with a solitary EMP of the small intestine. The female patient refused treatment. At follow-up 3 months postoperatively, her disease progressed and she newly developed multiple LNs and nodular lesions in the right pelvic side wall. She was treated with dexamethasone. The male patient experienced back pain 25 days after Whipple's operation. Spine series magnetic resonance imaging revealed an intermediate signal intensity mass in the posterior epidural space from T8/9 to T10. The mass was removed, and the same histologic features were identified as duodenal masses. He was treated with dexamethasone and radiotherapy., Conclusions: EMPs of the small intestine are easy to overlook because they rarely occur in the small intestine. Although surgery is not required for diagnosis, surgical resection can be a good option for EMPs of the small intestine, instead of local radiation therapy. However, close follow-up is required due to the possibility of relapse or progression to plasma cell myeloma., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)