A 67-year-old woman diagnosed with primary hyperparathyroidism and a medical history of fatty liver was hospital-ized in February 2017 to undergo a parathyroidectomy for a well-defined flat single parathyroid adenoma in the left lobe that measured 15 mm. There was no family history of hypercalcemia. Although she had been infected with the influenza A virus 3 weeks prior and suffered from an URTI several days before, vital signs and physical findings were not remarkable on the day of admission. Initial blood test results revealed features of hyperparathyroidism, a high concentration of C-reactive protein (CRP), anemia, and liver function disorder, including the following measurements: white blood cell (WBC) count 6.3x109/L, hemoglobin 94 g/L, platelets 374x109/L, albumin 31 g/L, CRP 68.5 mg/L, aspartate aminotransferase 29 U/L, alanine aminotransferase 69 U/L, alkaline phosphatase 1015 U/L,  -glutamyl transferase 197 U/L, creatine kinase 15 U/L, amylase 53 U/L, creatinine 47.7 micromol/L, blood urea nitrogen 4.7 mmol/L, sodium (Na) 143 mmol/L, potassium (K) 4.0 mmol/L, chlorine (Cl) 108 mmol/L, calcium (Ca) 3.02 mmol/L, phosphorus (P) 0.94 mmol/L, intact parathyroid hormone 16.2 pmol/L, parathyroid hormone-related protein <1.1 pmol/L, and 1,25-(OH)2 vitamin D 242.4 pmol/L.
For surgery, the approach was started with a 4 cm lateral incision. Bleeding totaled 3 mL and the procedure was performed without any complications, after which hypercalcemia showed remission. However, a moderate fever developed 2 days after surgery (Figure 1), though there were no other symptoms such as fatigue, pain, or physical findings including surgery scar redness, joint swelling, or eruption. Body temperature never exceeded 38 C and the greatest fluctuation was within 1 C. Computed tomography (CT) scanning performed just prior to surgery revealed no remarkable findings, such as tuberculosis or abscess. Although the operation was a relatively minor procedure, the fever was considered to be the result of the healing process and the patient continued to be followed. When given acetaminophen as rescue, the fever declined, though emerged again and rose to 38 C on postoperative day 6 (Figure 1). Furthermore, blood test results showed that a moderately high concentration of CRP (79.8 mg/L) remained, though there was no increase in WBC (Table 1). For symptomatic treatment, daily administrations of acetaminophen were started, which controlled the fever.
To investigate further, screening for collagen disease including vasculitis was performed, including erythrocyte sedimentation rate (ESR), rheumatoid factor, anti-cyclic citrullinated peptide antibody, antinuclear antibody, serum complement titer, antineutrophil cytoplasmic antibody, and serum ferritin. Thereafter, the patient was discharged on postoperative day 10 and asked to return on an outpatient basis. Surprisingly, pain in both shoulders and morning stiffness lasting for >1 hour suddenly appeared 3 days after discharge. The pain was too severe to sit up, and thus, the patient returned to our hospital. Our examination found no evidence of eruption, peripheral pitting edema, or tumor in a temporal artery. Furthermore, a screening blood test for collagen disease performed before discharge was negative (data not shown), except for ESR (113 mm/h), though an elevated concentration of CRP (112.4 mg/L) and high level of ESR (101 mm/h) were noted (Table 1). A CT scan did not reveal any inflammatory findings including vasculitis. Based on the symptoms and blood test results, though without joint sonography findings, the patient had >4 points in the American College of Rheumatology and European League Against Rheumatism classification criteria and disease activity as assessed by PMR activity score was >17 points. Therefore, we made a diagnosis of PMR and low-dose prednisolone was started, after which the symptoms rapidly improved and inflammation was reduced within a few days (Table 1). Body temperature, which had been under control with acetaminophen, remained controlled after switching to prednisolone. After 1 year of treatment, the dose of prednisolone was successfully reduced in February 2018.
Written informed consent was obtained from the patient to use anonymized information from their medical records and the CT scan and laboratory test results. The patient granted permission for the publication of all anonymized information.