Received Mar 18, 2026
| Type | Name | Manufacturer | Dose | Lot | Route / Site |
|---|---|---|---|---|---|
| RSV | RSV (NO BRAND NAME) | UNKNOWN MANUFACTURER | 1 | — | — |
22% circulating monoclonal plasma cells; The initial case was missing the following minimum criteria: No AE Upon receipt of follow-up information on (11Mar2026), this case now contains all required information to be considered valid. This is a literature report for the following literature source(s): A 77-year-old female patient received rsv vaccine prot.subunit pref 2v (RSV VACCINE PROT.SUBUNIT PREF 2V), as dose 1, single (Batch/Lot number: unknown) for immunisation. The patient's relevant medical history included: "stage IVa high-grade serous carcinoma of the ovary" (unspecified if ongoing); "Hypertension" (unspecified if ongoing); "Hyperlipidemia" (unspecified if ongoing); "Anxiety" (unspecified if ongoing); "Drug-induced polyneuropathy" (unspecified if ongoing); "Ovarian cancer" (unspecified if ongoing). The patient's concomitant medications were not reported. The following information was reported: PLASMA CELLS INCREASED (medically significant), 4 days after the suspect product(s) administration, outcome "recovered", described as "22% circulating monoclonal plasma cells". The patient underwent the following laboratory tests and procedures: Biopsy lymph gland: patient underwent port placement and was, notes: discharged in stable condition at an external oncology institution with plans to start single-agent carboplatin for recurrence of metastatic ovarian carcinoma; Blood culture: negative; Blood smear test: 22 %, notes: atypical plasma cells with associated red blood cell rouleaux formation; negative, notes: for the previously observed population of atypical plasma cells and Rouleaux formation; Electrophoresis protein: normal protein profiles without an M-spike observe; unremarkable, notes: with a normal kappa/lambda ratio and absence of M-protein; Flow cytometry: demonstrated lambda-restricted plasma cells, notes: expressing CD19+, CD27+, CD38+, CD56-, and CD138+ and lacking expression of CD20, CD56, and CD117, with cytoplasmic lambda light chain restriction (22,482 plasma cell events with cytoplasmic kappa: lambda ratio of 0.0; normalization to polyclonal plasma cells, notes: repeat flow cytometry 6 days later: revealed normalization to polyclonal plasma cells; showed a mixture of B-cells, notes: (surface kappa:lambda = 2.3) and T-cells, with lack of support for aberrant plasma cell population (29 polytypic plasma cell events showing cytoplasmic kappa:lambda ratio of 1.5); HIV test: Negative; Imaging procedure: showed increasing diaphragmatic, notes: retroperitoneal pelvic, and right inguinal adenopathy concerning for recurrence of malignancy; Immunoassay: unremarkable, notes: with a normal kappa/lambda ratio and absence of M-protein; showed polytypic IgA at, notes: the upper limit of normal but was otherwise normal; Light chain analysis: normal; 0.05; 2.5; 1.22, notes: normal by serum immunofixation electrophoresis (SIFE) test; 2.3; 1.5; Monoclonal immunoglobulin: absence; Pathology test: negative; Examination: showed lower extremity edema, notes: and post-surgical changes but was otherwise unremarkable; Protein urine: normal protein profiles without an M-spike observe; Serology test: negative; Vital capacity: stable; White blood cell count: 20.6 x10 9/l; 11.74 x10 9/l, notes: Her admission labs; White blood cell count: 22,482, notes: during routine preoperative testing. Clinical course: The patient is a 77-year-old female with a history of stage IVa high-grade serous ovarian cancer complicated by brain metastasis, status post resection and previous treatment, hypertension, hyperlipidemia, anxiety, and drug-induced polyneuropathy, who initially presented for preoperative labs prior to planned port placement. The patient obtains oncology care at an external institution and was referred to our institution for port placement after surveillance imaging showed increasing diaphragmatic, retroperitoneal pelvic, and right inguinal adenopathy concerning for recurrence of malignancy. The patient last received chemotherapy about 1 year prior. She was noted to have received the RSV vaccine 4 days prior to presentation for preoperative labs. During preoperative laboratory testing, the patient was found to have leukocytosis (white blood cell count of 20.6 × 109/L). Peripheral blood smear demonstrated 22% atypical plasma cells with associated red blood cell rouleaux formation (Fig. 1A and B). Flow cytometric analysis of peripheral blood revealed an increased population (22.4%) of monoclonal plasma cells expressing CD19, CD27, CD38, CD81, and CD138, and lacking expression of CD20, CD56, and CD117, with cytoplasmic lambda light chain restriction (22,482 plasma cell events with cytoplasmic kappa:lambda ratio of 0.05) (Figs. 2 and 4A). The presence of surface light chain expression may suggest that this population represents a spectrum of differentiation, ranging from plasmacytoid B-cells to more mature plasma cells, as fully differentiated plasma cells typically lack surface immunoglobulin expression. These findings were concerning for a plasma cell neoplasm. Aside from this population of atypical plasma cells, no aberrant B- or T-cell populations were identified (B-cell surface kappa:lambda ratio of 2.5). She completed outpatient infectious work-up including viral respiratory pathogens, which were reportedly negative, but records were not accessible in our electronic medical records. She was admitted 5 days later for evaluation of suspected plasma cell neoplasm. On admission, the patient's vitals were stable, and she was asymptomatic. Examination showed lower extremity edem and post-surgical changes but was otherwise unremarkable. Her admission labs showed leukocytosis (WBC 11.74), with peripheral blood smear negative for the previously observed population of atypical plasma cells and Rouleaux formation. Serum and urine protein electrophoresis showed normal protein profiles without an M-spike observed. The patient's kappa/lambda light chain ratio was normal (1.22) by serum immunofixation electrophoresis (SIFE) test. Repeat flow cytometry showed a mixture of B-cells (surface kappa:lambda = 2.3) and T-cells, with lack of support for aberrant plasma cell population (29 polytypic plasma cell events showing cytoplasmic kappa:lambda ratio of 1.5) (Figs. 3 and 4B). Immunofixation showed polytypic IgA at the upper limit of normal but was otherwise normal. Blood cultures collected at admission returned negative. Hepatitis serologies and HIV testing were negative. Given the differential findings, extensive investigation was carried out to rule out the possibility of blood sample error or contamination, which confirmed both the original and repeat samples as belonging to the patient. Given absent serological evidence of MM, bone marrow biopsy was deferred. The patient underwent port placement and was discharged in stable condition for lymph node biopsy at an external oncology institution with plans to start single-agent carboplatin for recurrence of metastatic ovarian carcinoma. Conclusion: This case highlights a rare and previously undocumented immune response following RSV vaccination, characterized by a transient population of peripherally circulating monoclonal plasma cells. While plasma cell neoplasms, such as multiple myeloma and MGUS, are well documented in the literature, this case underscores the importance of considering alternative explanations for atypical lab findings in patients with recent immunizations, particularly in the context of newly approved vaccines. The observation of a monoclonal plasma cell population post-vaccination, without accompanying serological or clinical evidence of a plasma cell neoplasm, suggests that the immune response triggered by the RSV vaccine may mimic, albeit transiently, features typically associate with plasma cell disorders. This phenomenon underscores the complexity of the immune system's response to novel vaccines, especially in patients with pre-existing conditions or immunocompromised states. Further research is needed to elucidate the mechanisms underlying this atypical response and to determine whether similar phenomena might be observed with other vaccines or in different patient populations. Clinicians should remain vigilant in distinguishing between true neoplastic processes and vaccine-induced immune responses to avoid unnecessary invasive procedures and ensure appropriate patient management.; Sender's Comments: Based on the available information, the causal association between the event Plasma cells increased and the suspect product rsv vaccine prot.subunit pref 2v can not be excluded. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.
Medical History/Concurrent Conditions: Anxiety; Hyperlipidemia; Hypertension; Ovarian cancer; Ovarian cancer stage IV; Polyneuropathy
Test Name: lymph node biopsy; Result Unstructured Data: Test Result:patient underwent port placement and was; Comments: discharged in stable condition at an external oncology institution with plans to start single-agent carboplatin for recurrence of metastatic ovarian carcinoma.; Test Name: Blood culture; Test Result: Negative ; Test Name: Peripheral blood smear; Test Result: 22 %; Comments: atypical plasma cells with associated red blood cell rouleaux formation; Test Name: Peripheral blood smear; Result Unstructured Data: Test Result:negative %; Comments: for the previously observed population of atypical plasma cells and Rouleaux formation.; Test Name: Serum protein; Result Unstructured Data: Test Result:normal protein profiles without an M-spike observe; Test Name: Serum protein electrophoresis; Result Unstructured Data: Test Result:unremarkable; Comments: with a normal kappa/lambda ratio and absence of M-protein; Test Name: Flow cytometry; Result Unstructured Data: Test Result:demonstrated lambda-restricted plasma cells; Comments: expressing CD19+, CD27+, CD38+, CD56-, and CD138+ and lacking expression of CD20, CD56, and CD117, with cytoplasmic lambda light chain restriction (22,482 plasma cell events with cytoplasmic kappa: lambda ratio of 0.0; Test Name: Flow cytometry; Result Unstructured Data: Test Result:normalization to polyclonal plasma cells; Comments: repeat flow cytometry 6 days later: revealed normalization to polyclonal plasma cells; Test Name: Flow cytometry; Result Unstructured Data: Test Result:showed a mixture of B-cells; Comments: (surface kappa:lambda = 2.3) and T-cells, with lack of support for aberrant plasma cell population (29 polytypic plasma cell events showing cytoplasmic kappa:lambda ratio of 1.5); Test Name: HIV testing; Test Result: Negative ; Test Name: imaging; Result Unstructured Data: Test Result:showed increasing diaphragmatic; Comments: retroperitoneal pelvic, and right inguinal adenopathy concerning for recurrence of malignancy.; Test Name: immunofixation; Result Unstructured Data: Test Result:unremarkable; Comments: with a normal kappa/lambda ratio and absence of M-protein; Test Name: immunofixation; Result Unstructured Data: Test Result:showed polytypic IgA at; Comments: the upper limit of normal but was otherwise normal.; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:normal; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:0.05; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:2.5; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:1.22; Comments: normal by serum immunofixation electrophoresis (SIFE) test; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:2.3; Test Name: kappa/lambda ratio; Result Unstructured Data: Test Result:1.5; Test Name: M-protein; Result Unstructured Data: Test Result:absence; Test Name: viral respiratory pathogen; Test Result: Negative ; Test Name: Examination; Result Unstructured Data: Test Result:showed lower extremity edema; Comments: and post-surgical changes but was otherwise unremarkable; Test Name: urine protein; Result Unstructured Data: Test Result:normal protein profiles without an M-spike observe; Test Name: Hepatitis; Test Result: Negative ; Test Name: vitals; Result Unstructured Data: Test Result:stable; Test Name: leukocyte; Result Unstructured Data: Test Result:20.6 x10 9/l; Test Name: leukocyte; Result Unstructured Data: Test Result:11.74 x10 9/l; Comments: Her admission labs; Test Name: monoclonal plasma cells; Result Unstructured Data: Test Result:22,482; Comments: during routine preoperative testing