IntroductionSarcoidosis is a multiorgan disease of unknown cause characterized by the formation of granulomas in various organs. Intrathoracic lesions are seen in 90% of patients, and are associated with symmetric bilateral portal lymphadenopathy and diffuse pulmonary nodules.1) Nonspecific systemic symptoms of sarcoidosis include fever, which in most cases is mild, but can sometimes reach 39-40°C. 2) Impaired concentration is also a common symptom reported in sarcoidosis patients, and it has been reported that this may be due to various complications associated with sarcoidosis. Steroid therapy has been reported to have an improving effect on cognitive impairment associated with sarcoidosis.3),4)Heerfordt syndrome is a type of sarcoidosis characterized by a combination of facial nerve paralysis, parotid gland enlargement, and uveitis, and is said to be accompanied by a mild fever.5) Cases with all three symptoms are called ”complete Heerfordt syndrome” (0.3% of sarcoidosis patients). Cases with only two of the three characteristic symptoms are called ”incomplete Heerfordt syndrome” (1.3%). 6)We report a rare case of incomplete Heerfordt syndrome.Case History/examinationPatient: 78-year-old female.Medical history: hypertension, IgA nephropathy, facial nerve paralysis, blurred vision, heart failureMedication history:One vonoprazan fumarsate tablet 20mg after breakfast, one azilsartan tablet 20mg after breakfast, one amlodipine tablet 5mg after breakfast, one furosemide tablet 20mg after breakfast, one trichlormethiazide tablet 1mg after breakfastChief complaint: feverHistory of current illness: One year prior to the visit, the patient had facial nerve paralysis and blurred vision, and had been receiving outpatient follow-up treatment at the otolaryngology and ophthalmology departments. 14 days prior to the visit, the patient developed a fever of 38 degrees and visited our hospital.Vital signs at time of admission: Consciousness level: GCS E4V5M6, BP: 120/69mmHg, HR: 90 beats/min RR: 18 beats/min, BT: 37.9℃, SpO2: 100% (room air)Physical findings: No swelling or tenderness in cervical lymph nodes. No pharyngeal redness. Regular heart sounds, no lung noises.Abdomen flat and soft, no tenderness. No lower limb edema.Differential Diagnosis, Investigations, and TreatmentBlood test findings: High values of IL-2 receptor 3670U/mL and ACE 27.4U/L were observed.(Table 1).Image findings: Plain chest CT showed swelling of the mediastinal lymph nodes. (Figure 1a, b).Pathological findings: Non-caseating epithelioid cell granuloma was observed (Fig. 2a, b, c)Fundus findings: Pale opacity around the blood vessels along the optic nerve suggested retinal vasculitis, and anterior chamber inflammation was observed, leading to a diagnosis of uveitis. (Fig. 3)Since the patient’s visit to the hospital, the patient had a fever and pyuria in the urine, so treatment was started with CTRX 2g/day. The fever persisted even after antibiotics were started, and a CT scan at the time of the visit showed swelling of the medial lymph nodes. A blood test showed elevated IL-2 receptor and ACE, so malignant lymphoma and sarcoidosis were raised as differential diagnoses, and since the patient also requested a detailed examination, a surgical lymph node biopsy was performed. A lymph node biopsy was performed on the 16th day of hospitalization, and pathological findings showed non-caseating epithelioid cell granuloma, leading to a diagnosis of sarcoidosis. On the 23rd day of hospitalization, an ophthalmologic examination revealed membrane vasculitis with faint perivascular opacity along the optic nerve, as well as inflammation of the parotid gland, leading to a diagnosis of uveitis, findings consistent with ocular sarcoidosis. On the 25th day of hospitalization, an otorhinolaryngological examination revealed no abnormal findings, and MRI did not reveal swelling of the parotid gland.Outcome and follow-upAlthough the patient’s fever and fever were repeated, oral steroid treatment tended to improve the patient’s fatigue, so the decision was made to follow up the patient on an outpatient basis without oral steroid treatment, and the patient was discharged on the 42nd day of hospitalization.Discussion:Cases with all three symptoms of fever, facial nerve paralysis, parotid gland swelling, and uveitis are called ”complete Heerfordt syndrome,” while cases with two symptoms are called ”incomplete Heerfordt syndrome.” Darlington et al. investigated the characteristics of sarcoidosis and reported that of 1,000 patients with sarcoidosis, only 3 (0.3%) had complete Heerfordt syndrome and 13 (1.3%) had incomplete Heerfordt syndrome. 7) This case was diagnosed as incomplete Heerfordt syndrome because there was no swelling of the parotid gland.Heerfordt syndrome was first described by Heerfordt and Waldenstrom in 1909, and its association with sarcoidosis was noted in 1937.8), 9) Because Heerfordt syndrome is a rare disease, no standard treatment strategy has been established. However, in cases where facial nerve paralysis is frequently observed, corticosteroid treatment based on neurosarcoidosis is applied. 10)Although the initial response rate to corticosteroids is high, symptoms may recur during tapering of corticosteroids. In these cases, immunosuppressants such as azathioprine, methotrexate, cyclosporine A, and cyclophosphamide are used in combination with corticosteroids.11) In this case, the facial nerve paralysis symptoms remained, and although steroid treatment was indicated, the patient requested that steroids not be administered, and the policy was to observe the patient’s condition. The policy is to administer steroids according to the patient’s symptoms and wishes.Sarcoidosis presents various clinical symptoms. Regardless of whether symptoms are present or not and whether the disease is acute or not, sarcoidosis affects various organs and can have clinical effects ranging from benign to very severe. 11) Previous reports have shown that 5% of sarcoidosis cases are fatal. 12)Incomplete Heerfordt syndrome is a rare disease, but symptoms appear gradually and may appear as an early symptom of sarcoidosis.10) Based on these findings, when fever is observed in addition to systemic symptoms such as blurred vision, facial nerve paralysis, and parotid gland swelling, Heerfordt syndrome, a subtype of sarcoidosis, should be recalled and systemic observation should be performed early to differentiate from sarcoidosis.Key Clinical MessageWe have experienced a rare disease called Heerfordt syndrome. When fever is observed in addition to early symptoms such as facial nerve paralysis and parotid gland swelling, Heerfordt syndrome, a subtype of sarcoidosis, should be recalled and systemic observation should be performed early to differentiate from sarcoidosis.Author ContributionsDr. Motoyasu Nakamura(Corresponding Author):Writing - original draft, Mx. Eriko Yoshida:Supervision, Dr. Hiroto Sasage:Data curation,Formal analysis,Funding acquisition,Dr. Kenta Watanabe:Methodology,Project administration,Resources,Visualization,Writing - original draft, Dr. Satoshi Suzuki:Conceptualization,Writing - review & editingThere are no conflicts of interest to disclose regarding this submission.Written informed consent was obtained from the patient for the publication of this case report