Zhaxi finished the examination, stood by the bedside pondering for a while before leaving the ward; the patient’s wife immediately followed out.

"Doctor Zhaxi, I’m sorry for just now, I mistook you for an ordinary young doctor, I didn’t expect you were a student of Professor Yang," the patient’s wife explained apologetically.

Zhaxi smiled and said, "It’s alright, don’t worry, we’ll do our utmost."

"Okay, thank you, thank you!" The patient’s wife felt reassured.

Upon returning to Yang Ping’s office, Yang Ping was still reading the literature, and Director Liu had already left.

"How is it going?" Yang Ping put down the literature.

Zhaxi sat down and recounted what he had found. After speaking, he looked at Yang Ping, "Professor Yang, this patient’s condition is very complex. Fever, joint pain, rashes are indicative of rheumatic immune diseases. But all autoantibodies are negative. The confusion indicates central nervous system involvement, but the cerebrospinal fluid is normal. I can’t figure it out."

Yang Ping looked at him without answering and instead asked, "With the experience of the previous really difficult case, this time you should be more at ease."

Zhaxi thought for a moment and said, "I need to research the literature, this disease is too atypical, I need to see if there are any similar case reports." 𝑓𝑟𝑒𝘦𝓌𝑒𝑏𝑛𝑜𝘷𝑒𝘭.𝒸𝘰𝑚

Yang Ping nodded, "Alright, go ahead and check."

Zhaxi returned to the study room, opened his computer, and began searching on PubMed. He used several keyword combinations, fever, arthralgia, rash, encephalopathy, negative autoantibodies. There weren’t many articles, he looked through the titles and abstracts one by one, then used translation software to translate them, and found an available Doctor to verify them, now understanding the importance of English.

He found a case report from the New England Journal of Medicine, titled "An Adult Case of Still’s Disease Presenting with Fever, Arthralgia, Rash, and Encephalopathy." Zhaxi clicked on the full text and quickly browsed through it. The patient described in the case report was almost identical to the patient he saw in the ward, a middle-aged man with fever, joint pain, rash, and later confusion. All autoantibodies were negative, slight elevations in erythrocyte sedimentation rate and C-reactive protein, normal cerebrospinal fluid, and finally diagnosed as adult Still’s disease.

Zhaxi’s heartbeat quickened, and he continued reading. The article explained that adult Still’s disease is a rare autoinflammatory condition of unknown etiology, primarily manifesting with fever, joint pain, and rash, and can affect multiple systems, including the central nervous system. Diagnosis lacks specific laboratory markers, mainly relying on clinical standards and excluding other diseases. Currently, the commonly used diagnostic standard is the Yamaguchi criteria, main criteria: fever ≥39 degrees lasting over a week, joint pain lasting over two weeks, typical rash, leukocytes ≥10×10⁹/L; secondary criteria: sore throat, lymphadenopathy, hepatosplenomegaly, liver function abnormalities, rheumatoid factor, and antinuclear antibody negative. Diagnosis requires five or more items, of which at least two are main criteria.

Zhaxi noted down the Yamaguchi criteria to compare with the patient’s clinical manifestations. Fever — present, but only a bit over thirty-eight degrees, not reaching thirty-nine degrees, doesn’t meet the main criteria. Joint pain — present, lasting six months, meets the main criteria. Typical rash — present, meets the main criteria. Leukocytes — normal, doesn’t meet the main criteria. Sore throat — patient didn’t mention it, doesn’t meet the secondary criteria. Lymphadenopathy — not detected in the patient, doesn’t meet the secondary criteria. Hepatosplenomegaly — absent, doesn’t meet the criteria. Liver function abnormalities — patient’s liver function is normal, doesn’t meet the criteria. Negative autoantibodies — meets the secondary criteria. Total is three items — joint pain, rash, negative autoantibodies. Not enough for five items.

Zhaxi frowned, not meeting the Yamaguchi criteria, it’s not adult Still’s disease. He continued reading the literature. Later, there was a review discussing atypical presentations of adult Still’s disease. The article stated that some patients may not reach thirty-nine degrees for their fever, and some might have normal leukocytes. For these atypical cases, diagnosis is more challenging and requires excluding all other possibilities.

He set aside this article and found a few related ones. One article from the Annals of Rheumatic Diseases discussed a spectrum of diseases called "autoinflammatory syndromes." The article mentioned that some patients present with recurrent fevers, joint pain, and rashes but don’t meet any known autoinflammatory disease diagnostic criteria. These patients might belong to an "unclassified autoinflammatory syndrome." Diagnosis relies on clinical manifestation and exclusion of other diseases. Treatment with glucocorticoids and IL-1 antagonists might be effective.

Zhaxi printed out these articles and looked up information on autoinflammatory diseases. He spent an entire afternoon reviewing all related literature. Then he drew a mind map in his notebook, centering on the patient’s symptoms, listing all possible diagnoses, then using the method of exclusion one by one.

Infectious diseases — the patient has had recurrent fevers for half a year, but no localized signs of infection, pathogenic examination negative, ineffective anti-infective treatment, unlikely. Tumorous diseases — no evidence of a primary tumor in the patient, tumor markers normal, PET-CT not yet done, but also unlikely. Rheumatic autoimmune diseases — the patient has fever, joint pain, rash, but all autoantibodies negative, doesn’t fit typical rheumatic autoimmune diseases. Autoinflammatory diseases — possible, but unclear which specific kind. Drug reactions — the patient has no history of long-term medication, excluded. Hyperthyroidism — the patient’s thyroid function is normal, excluded...