Solitary extramedullary plasmacytoma in the hilar region: A case of minimal marrow involvement in an elderly male

Abstract

Introduction and importance

Solitary extramedullary plasmacytoma (SEP) is a rare plasma cell neoplasm, constituting around 3 % of plasma cell malignancies. SEP typically presents as a single tumor, either in bone or soft tissue, without systemic disease, and is often misdiagnosed due to its nonspecific symptoms. Diagnosis requires biopsy and extensive imaging studies to exclude multiple myeloma and other malignancies. Here, we present a case of SEP located in the hilar region, initially suspected to be a lung malignancy.

Case presentation

A 70-year-old male with a history of hepatitis C presented with hemoptysis and shortness of breath. PET-CT revealed a metabolically active mass in the left hilar region, encasing major vascular structures and obstructing the left upper lobe bronchus, suggesting a neoplastic process. Transbronchial biopsy showed lymphoproliferative disease, and immunohistochemistry revealed monoclonal plasma cells, confirming SEP. Laboratory tests indicated mild monoclonal gammopathy, and bone marrow aspirate showed minimal involvement with plasma cells. A diagnosis of SEP with minimal marrow involvement was made.

Clinical discussion

Extramedullary plasmacytomas are typically found in the head and neck, but rarer cases, like this one in the hilar region, may mimic lung cancer. A comprehensive diagnostic approach, including imaging, biopsy, and bone marrow analysis, is essential for accurate diagnosis and management.

Conclusion

This case underscores the importance of a multidisciplinary approach in diagnosing SEP, which can be easily confused with lung malignancy. Early detection and treatment, including surgery and radiotherapy, lead to favorable outcomes and reduced recurrence rates.

1. Introduction

Solitary extramedullary plasmacytoma (SEP) is an uncommon form of plasma cell dyscrasia characterized by the proliferation of neoplastic monoclonal plasma cells, presenting as a localized tumor in either bone or soft tissue without systemic disease. SEP accounts for approximately 3 % of plasma cell malignancies. It typically presents in the fifth to seventh decade of life and is more prevalent in males, with a male-to-female ratio of 3:1. The most frequent sites of SEP are the upper aerodigestive tract, including the oropharynx, nasal cavity, and paranasal sinuses, which account for up to 80 % of cases. Other less common sites include the gastrointestinal tract, central nervous system, skin, and breast. Patients typically present with localized symptoms related to the tumor's anatomic location, such as nasal obstruction, epistaxis, or a visible mass. Constitutional symptoms, such as weight loss and fatigue, are rare due to the absence of systemic disease [1]. In SEP with minimal marrow involvement, there is biopsy proven solitary lesion in either bone or soft tissue with evidence of clonal plasma cells (bone marrow plasma cells <10 % for minimal marrow involvement); normal skeletal survey on MRI/CT(except for primary solitary lesion); absence of end-organ damage such as CRAB symptoms or any signs of multiple myeloma [2]. Accurate diagnosis necessitates biopsy of the suspected lesion, along with comprehensive laboratory and imaging studies, following stringent criteria. We report a case of solitary plasmacytoma in hilar region with minimal marrow involvement with a clincioradiological suspicion of lung malignancy.

2. Case presentation

A 70-year-old male presented with chief complaints of hemoptysis and shortness of breath (with Hepatitis C status positive). There were no other systemic signs and symptoms. Whole body Positron emission tomography-computed tomography (PET-CT) scan revealed metabolically active soft tissue density mass lesion seen in left hilar region, causing complete cut off of left upper lobe bronchus, encasing left pulmonary artery and superior pulmonary vein-likely neoplastic. No other lesion was identified anywhere else in the body. Following this ultrasound guided transbronchial needle aspiration (EBUS-TBNA) was performed and cytological assessment was suggestive of lymphoproliferative disease possibly lymphoplasmacytic lymphoma as was showing presence of lymphocytes, plasmacytoid cells and many plasma cells [Fig. 1]. Histopathological examination showed sheets of mature and immature plasma cells with positivity for CD38, CD138 and lambda light chain restriction [Fig. 2]. The patient was advised further work-up for possibility of multiple myeloma, and Waldenstorm macroglobulinemia. Laboratory investigations of myeloma panel were done which revealed elevated levels of serum beta-2 microglobulin (7215 ng/l); M-spike (0.79 g/dl); kappa free light chain (149.37 mg/l); lambda free light chain (90.32 mg/l); kappa/lambda ratio = 1.65; IgG (3212 mg/dl); while IgA and IgM were within normal limits. Serum electrophoresis showed positivity for IgG and Kappa with raised total protein (8.52 g/dl); and gamma globulin (2.76). The complete blood counts and peripheral smears were within normal limits with no evidence of any rouleaux formation. Bone Marrow Aspirate showed cellular smears with normoblastic maturation of erythroid series, normal sequential maturation of myeloid series and megakaryocytes also seen with M: E ratio of 1.4:1. Myelogram revealed the presence of eight plasma cells leading to minimal marrow involvement.

Fig. 1.

Radiological and cytological findings

a) Computed tomography scan showed FDG avid soft tissue density mass lesion seen in left hilar region measuring 53 ∗ 40 ∗ 40 mm.

b, c) Cytopathological examination revealed atypical lymphocytes, plasmacytoid cells and plasma cells suggesting a possibility of lymphoproliferative disease.

Fig. 2.

Histopathological and immunohistochemical findings

a) H&E stained sections showing sheets of typical and atypical plasma cells.

b) On immunohistochemistry, these cells were positive for CD38, and CD138 with lambda restriction.

The tumor was surgically excised through a left upper lobectomy—a lung-sparing procedure to remove the tumor while maintaining pulmonary function. Operative notes highlighted careful dissection to preserve adjacent pulmonary structures and ensure complete tumor removal. Thus, a final diagnosis of solitary plasmacytoma of the hilar region with minimal marrow involvement was made. The tumor was excised followed by radiotherapy. The patient is currently under follow-up with no evidence of any recurrence.

3. Discussion

Plasma cell neoplasms, also known as plasma cell dyscrasias, encompass a range of disorders characterized by the abnormal proliferation of clonal plasma cells that produce a monoclonal immunoglobulin. These neoplasms can manifest as a solitary lesion, termed solitary plasmacytoma, or as multiple lesions in multiple myeloma [3]. Solitary plasmacytoma most commonly occurs in bone but can also appear in soft tissues outside the bone (known as extramedullary plasmacytoma). SEP of the hilar region is extremely rare and can be easily misdiagnosed as lung malignancy due to its overlapping clinical and radiological features.

SEP is most frequently found in the head and neck region, particularly in the upper aerodigestive tract but can also be found in GIT, CNS, and breast. Here, we present a very unusual case of SEP in the hilar region which can very easily be confused with lung malignancies. Our case presentation reported according to SCARE guidelines adds to this limited pool of knowledge, underlining the diagnostic and therapeutic complexities associated with this uncommon diagnosis [4]. Therefore, a complete work-up including radiological investigations, biopsy with immunohistochemistry, bone marrow studies and laboratory investigations are required in a definitive diagnosis of solitary extramedullary plasmacytoma. For instance, the tumor, in this case, was identified as lambda light chain-restricted plasmacytoma using markers CD38 and CD138, which are critical for differentiating SEP from other lymphoproliferative disorders.

A thorough and multidisciplinary approach will lead to early diagnosis and treatment hence improving the prognosis. Abdulfattah et al. reported a case of lymphoplasmacytic lymphoma with extramedullary Waldenström's macroglobulinemia in a 73-year-old female who presented with lung consolidation [5]. Nie et al. reported a case of solitary plasmacytoma of the lung who presented with enlargement of left lung hilum of chest X-ray [6]. Wang et al. and Maqsood et al. also reported cases of solitary pulmonary plasmacytoma respectively clinically misdiagnosed as lung malignancy similar to the present case [7,8]. In the previously reported cases of solitary pulmonary plasmacytoma, there was no evidence of recurrence/ progression and even the chest radiograph became unremarkable. However, Saidi et al. reported a case of pulmonary plasmacytoma in a case of multiple myeloma [9].

<7 % of patients with SEP will experience a local recurrence following tumoricidal radiation [3]. Approximately 10–15 % of patients with SEP will eventually develop multiple myeloma. In patients with SEP with minimal marrow involvement, the progression rate is notably higher (approximately 20 %). These patients have five-year overall survival rates ranging from 40 to 85 % [3]. The prognosis depends on early detection and effective therapy, including surgery and radiotherapy.

4. Conclusion

We presented a case of 70-year-old male with solitary extramedullary plasmacytoma in hilar region which was suspicious of lung malignancy with complaints of hemoptysis and shortness of breath. The role of multidisciplinary approach in diagnosing such cases is crucial for early diagnosis and preventing progression to multiple myeloma. The surgical excision via left upper lobectomy and subsequent radiotherapy exemplifies the importance of a multidisciplinary approach in ensuring accurate diagnosis and management. Future research should focus on improving diagnostic tools and establishing robust clinical guidelines for managing SEP.

CRediT authorship contribution statement

SZ and SA were responsible for the reporting and diagnosis of the case. RK and SA were major contributors to the writing of the manuscript while SZ were responsible for the article review and editing. All authors read and approved the final manuscript.

Ethical approval

This case study was conducted in accordance with the Declaration of Helsinki.

Ethics approval and consent to participate

Informed patient consent was taken. The study was done in accordance with the Declaration of Helsinki of 1975.

Guarantor

Sana Ahuja

Research registration number

Not applicable.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request

Funding

This research received no funding.

Declaration of competing interest

All authors declare that there is no conflict of interest regarding the publication of this report.

Data availability

Supporting data will be available upon reasonable request.