Hypercalcemia; multiple myeloma; flu-like symptoms; myalgia; This case was reported in a literature article and described the occurrence of hypercalcemia in a 65-year-old female patient who received Flu unspecified (Influenza vaccine) for prophylaxis.  On an unknown date, the patient received Influenza vaccine. On an unknown date, less than a week after receiving Influenza vaccine, the patient experienced hypercalcemia (serious criteria hospitalization), multiple myeloma (serious criteria hospitalization and GSK medically significant), influenza-like symptoms (serious criteria hospitalization) and myalgia (serious criteria hospitalization). The patient was treated with rehydration fluid (nos) (Crystalloids), diuretics nos (Loop Diuretic (Nos)), calcitonin, pamidronic acid (Pamidronate), hemodialysis dialysate solution, bortezomib, lenalidomide, dexamethasone and zoledronic acid. On an unknown date, the outcome of the hypercalcemia, multiple myeloma, influenza-like symptoms and myalgia were recovered/resolved.   The reporter considered the hypercalcemia, multiple myeloma, influenza-like symptoms and myalgia to be related to Influenza vaccine.  Additional details were provided as follows: This case was reported in a literature article and described the occurrence of hypercalcemia in a 65-years old female patient, who was vaccinated with unspecified inactivated influenza vaccine (manufacturer unknown) for prophylaxis.  No information on patient's medical history, family history, concurrent condition or concomitant medication was provided. On an unspecified date, 5 days prior to presentation, the patient received unspecified inactivated influenza vaccine (administration route and site unspecified, dosage unknown; batch number not provided). The age of vaccination was not provided but it could be 64 years or 65 years.  On an unspecified date, an unknown period after the vaccination, the patient presented with subjective myalgias lasting 2 days. Vital signs were stable. Complete Blood Count (CBC) and basic metabolic panel (BMP) were unremarkable. Serum calcium was 10.8 mg/dl. The patient was discharged on supportive therapy. The patient presented a day later with persistent flu-like symptoms. Labs revealed serum calcium being above 22 mg/dl, normal renal function, total protein, albumin, ACE levels; clear UA with no albuminuria; low PTH and 1, 25-(OH)2-Vitamin D3 levels; elevated PTHrP & viscosity levels. 24-hour urine collection revealed proteinuria (550 mg). Peripheral blood smear revealed rouleaux formation. Computed tomography (CT) scans of the chest, abdomen and pelvis revealed no obvious malignancy. Quantitative immunoglobulins revealed elevated IgA (2415 mg/dl), and concurrent suppression of IgG and IgM levels. Quantitative serum light chain measurement revealed normal levels of kappa and lambda, with an elevated Kappa: Lambda ratio of 2:1. Serum Protein Electrophoresis (SPEP), Urine Protein Electrophoresis (UPEP), and serum immunofixation revealed IgA-Kappa multiple myeloma (MM). Given her severe-symptomatic hypercalcemia, the patient was treated with aggressive intravenous crystalloids, loop diuretics, calcitonin, pamidronate, and hemodialysis. The patient's calcium subsequently normalized to 10.1 mg/dl. Bone-marrow biopsy revealed intracytoplasmic kappa-restricted monoclonal plasma cells that occupied 40% of the marrow. Bone survey was negative for lytic lesions. The patient was started on bortezomib, lenalidomide, dexamethasone and monthly zoledronic acid; and the patient had not attained remission from myeloma yet. This case has been considered as serious due to hospitalization. The author commented, "Multiple myeloma (MM) is characterized by the neoplastic proliferation of immunoglobulin-producing plasma cells. Several cytokines, including IL-1, IL-6 and TNF-beta, derived from myeloma cells are thought to accelerate osteoclastic bone resorption and cause hypercalcemia through a paracrine mechanism. Our case is unique in that the patient initially had a normal serum calcium level that had increased rapidly to over 22 mg/dl within a period of 24 hours, had no renal failure or any bone involvement; and had a normal quantitative serum light chain measurement. It is theorized that the inactivated influenza vaccine given prior to presentation unmasked an atypical presentation of MM. This may be attributed to a vaccination induced cytokine storm, especially IL-6 mediated, that may be the key in the pathophysiology of hypercalcemia related to MM." This article corresponding to this case is not available for regulatory submission due to copyright restriction.