Prolonged, recurrent and periodic fever — branching viva

Opening

Examiner: How do you classify childhood fever that is prolonged, recurrent or periodic? [1]

Candidate: Three patterns. A single continuous illness beyond 7 to 14 days is prolonged fever, or fever of unknown origin. Several discrete episodes with the child well between is recurrent fever. Periodic fever is the subset where attacks recur at clockwork, stereotyped intervals. The pattern — not the height of the fever — drives the diagnosis, so I pattern it first before I order tests. [1]

Branch A — Recognising PFAPA

Examiner: This child has clockwork attacks every 5 weeks. What is the syndrome, and how do you confirm it? [2]

Candidate: PFAPA — periodic fever with pharyngitis, aphthous stomatitis and cervical adenitis. The tetrad Marshall described in 1987, with onset before 5 years, attacks lasting 3 to 6 days recurring every 3 to 8 weeks, and complete wellness between attacks. There is no confirmatory test — the diagnosis is clinical, from the Marshall and Thomas criteria and a documented diary, after excluding infection and the hereditary fevers. A CRP that rises during attacks and normalises between is supporting evidence. [2] [3] [4]

Probe: No confirmatory test — so how do you avoid over-investigating? [1]

Candidate: Recognise the pattern, document the diary over at least two attacks, and measure CRP during and between attacks. Once the criteria are met and the dangerous mimics excluded, I do not run serial batteries — that medicalises a benign syndrome. The error is treating PFAPA like an unsolved FUO. [1]

Branch B — The hereditary periodic fevers

Examiner: How do you tell PFAPA from the hereditary periodic fevers? [4]

Candidate: Two numbers and one feature. Attack duration sorts them fast: FMF is short at 1 to 3 days, PFAPA sits in the middle at 3 to 6 days, HIDS runs 3 to 7 days, and TRAPS is the outlier at 1 to 3 weeks. Interval regularity sorts them again — PFAPA is clockwork, cyclic neutropenia is a 21-day metronome, while FMF and HIDS are irregular. Then the signature feature confirms: periorbital oedema with a migratory rash over myalgia is TRAPS; serositis with an erysipelas rash in a Mediterranean child is FMF; aphthae and infection at a countable nadir is cyclic neutropenia. [4] [5]

Probe: What about HIDS specifically? [7]

Candidate: HIDS attacks last 3 to 7 days, are often triggered by vaccination, and bring a maculopapular rash with generalised lymphadenopathy and hepatosplenomegaly. I use the Steichen clinical criterion — immunisation-triggered attacks that are long and accompanied by rash and lymph nodes — to decide whether to pursue the diagnosis with serum IgD, urinary mevalonic acid and MVK genetic testing. [7]

Branch C — Management

Examiner: How do you treat an acute PFAPA attack? [3]

Candidate: A single oral dose of prednisolone 1 to 2 mg per kg aborts most attacks within hours, although it can shorten the interval to the next episode. Cimetidine prophylaxis benefits a subset with frequent attacks. For severe refractory disease, tonsillectomy is supported by three randomised trials and is reserved for after multidisciplinary discussion. PFAPA resolves spontaneously by adolescence, so the aim is symptom control, not cure. [3] [4]

Probe: And familial Mediterranean fever? [5]

Candidate: FMF is completely different in its stakes. I start lifelong colchicine, which prevents both the attacks and the development of AA amyloidosis. That is the critical point — untreated FMF causes amyloidosis and renal failure, while PFAPA never does. So the distinction between PFAPA and FMF is the single costliest error in this topic. [5] [6]

Branch D — Stumpers

Examiner: What must you not miss in a child with prolonged fever? [1]

Candidate: The dangerous mimics: malignancy, infective endocarditis, tuberculosis, Kawasaki disease and haemophagocytic lymphohistiocytosis. Fever with weight loss, night sweats, pallor or bruising points to malignancy and needs an urgent full blood count with film, not a recurrent-fever label. And fever in a neutropenic or immunocompromised host is a separate emergency that gets empiric broad-spectrum antibiotics first, not a FUO workup. [1]

Examiner: A child with five days of fever, conjunctivitis, a rash and red cracked lips — still a FUO workup? [1]

Candidate: No — that is Kawasaki disease, and the clock is ticking toward day 10 for intravenous immunoglobulin to protect the coronary arteries. I arrange an urgent echocardiogram and paediatric review, not a diary. [1]

Close

Examiner: One-line take-home. [1]

Candidate: Pattern the fever first — prolonged, recurrent or periodic; recognise PFAPA by its clockwork tetrad with normalising CRP and treat attacks with single-dose steroid; separate the hereditary fevers by attack duration and signature features; start lifelong colchicine for FMF to prevent amyloidosis; and never miss malignancy, endocarditis, Kawasaki disease, HLH or neutropenic-host fever. [1] [2] [5] [6]