Introduction

Multiple myeloma is a tumor of malignant plasma cells that consider as the second most common hematologic malignancy 1. This disease has an age-adjusted incidence of 4.7 cases per 100,000 populations 2. It often occurs in adults, and the mean age at diagnosis is 70 years 3. One of the most prominent features of this disorder is the presence of more than 10% clonal plasma cells in the bone marrow or biopsy associated with end-organ damage 2. Also, in 1846, Dalrymple and Bence Jones discovered an uncommon plasma cell tumor known as plasmacytoma 4. The etiology of plasmacytoma remains largely unknown, but factors such as viral pathogenesis have been identified and genetic factors may also be involved 5. The purpose of this paper is to report a 62-year-old man with a clinical and pathological history of multiple myeloma, who presented evidence of a mass in the retrobulbar area of the eye.

Case Presentation

In January 2018, a 62-year-old man was referred to our Clinic of Hematology and oncology, with one week of back pain history, and loss of consciousness in the neurological examination. Further analysis revealed the symptom of kidney failure. In primary laboratory investigations, he had normocytic normochromic anemia with Hb: 9.6g/dL, normal WBC and a decrease in platelet count (WBC: 8,300/mm; Platelet count: 79,000/mm). Also, renal function tests (RFT) and serum electrolytes were usually performed in multiple myeloma. The results of these tests showed hypergammaglobulinemia (5g/dL) and an increase in blood urea nitrogen (BUN) and serum creatinine (Cr) levels (BUN 64 mg/dL, Cr 8.1 mg /dL). Magnetic resonance imaging of the lumbar spine indicated vertebral collapse at T12 and L2. Examination of thebone marrow aspiration (BMA) and bone marrow biopsy revealed that a high percentage of plasma cells (>20% plasma cells) were negative for CD19, and positive for CD38, CD138 (Figure 1).

Our diagnosis was multiple myeloma and immediately started treatment with bortezomib, cyclophosphamide, and dexamethasone (the approved VCD is preferable as induction therapy for newly diagnosed multiple myeloma especially with renal failure). Also, zoledronic acid was used to reduce bone pain.

After 6 cycles, the initial response to treatment was relatively good. Five months later, the patient referred to an ophthalmologist with symptoms such as swelling of the right eyelid with ptosis, diplopia and blurred vision. In fundus examination, few scattered hemorrhages were seen in the left eye and the results of Visual Acuity for this eye were as follows: OD: 6/10, OS: 4/10. Also, the results of orbit computed tomography (CT) demonstrated a soft tissue mass (26 × 12 mm) in the retrobulbar of the left eye (Figure 2). In fine needle aspiration cytology (FNAC) of the mass, mature and immature plasma cells were observed, which led to the diagnosis of secondary extramedullary plasmacytoma. Thus, the patient underwent surgical debulking, the lesion was removed from the retrobulbar area and the result was successful. Currently, the patient’s condition is good, and he is continuing chemotherapy cycles with bortezomib and dexamethasone.

Discussion

Plasmacytoma, as an unusual tumor of malignant plasma cells, indicates 5-10% of all plasma cell neoplasms 6 and plasmacytoma can occur as a primary or secondary tumor, based on the presence or absence of systemic disease 7. Also, these neoplasms are divided into four different types: solitary plasmacytoma of bone (SPB), extramedullary plasmacytoma (EMP), multiple myeloma (MM) and plasma cell leukemia 8. The organs involved in the SPB are mainly axial skeletal bones, such as vertebra and skull, while in EMP, the head and neck, nasal cavity and nasopharyngeal are commonly involved 6. It has been reported that the rate of relapse after treatment for extramedullary plasmacytoma is 6-10% 9.

Also, MM is characterized by the proliferation of abnormal plasma cells and is usually limited to bone marrow 10. Extramedullary plasmacytoma has been reported in 3% of patients with MM 11. In these patients, orbital involvement is rare. According to the study performed by Burkat and colleagues 12, from 1972 to 2009, 52 cases of orbital multiple myeloma with a mean age of 56.5 have been reported and in 81% of them, the most common symptom was proptosis. Based on our reviews, from 2010 to 2018, about 20 cases have been described, which are listed in Table 1.

The mean age of these patients was 63.8 and in the many cases, orbital symptom has been unilateral (85%). The proptosis and diplopia were the most abundant orbital clinical symptoms involved, while ptosis, retrobulbar lesion, and low vision were less common (Table 2). Also, systemic chemotherapy and radiotherapy are good therapeutic options that in the most reports, the positive response to treatment has been reported 13. We reported a multiple myeloma patient with extramedullary plasmacytoma that was unique because of the unilateral retrobulbar lesion and its successful orbital surgery.

Conclusion

According to studies conducted to date, in patients with multiple myeloma, orbital symptoms often occur in adulthood and unilaterally. Additionally, the important point in these cases is that during differential diagnosis between the types of plasmacytomas, initially multiple myeloma should be considered.

List of abbreviations

BMA: bone marrow aspiration

BUN: blood urea nitrogen

CBC: complete blood count

Cr: creatinine

CT: computed tomography

EMP: extramedullary plasmacytoma

FNAC: fine needle aspiration cytology

MM: multiple myeloma

RFT: renal function tests

SPB: solitary plasmacytoma of bone

VCD: velcade (bortezomib), cyclophosphamide, and dexamethasone

Ethics approval and consent to participate

Yes

Competing interests

The authors declare that they have no financial or other conflicts of interest.

Funding

None.

Authors’ contributions

Mehrdad Payandeh & Noorodin Karami: Literature search, Clinical studies, Data acquisition, Data analysis;

Noorodin Karami: Manuscript preparation, Manuscript review, Guarantor;

Afshin Karami: Concepts, Design, Definition of intellectual content, Literature search, Manuscript editing;

Soode Enayati, Fatemeh Yari & Mehrnoush Aeinfar: Manuscript editing, Literature search.