Kimura disease is a chronic inflammatory disorder characterized by subcutaneous masses and regional lymphadenopathy in the head and neck region. Particularly seen in young men (20-40 years) of East Asian origin; M:F ratio is 3-7:1. Peripheral eosinophilia and elevated serum IgE almost always accompany. Most common presentation is painless subcutaneous mass(es) in the parotid/periauricular/submandibular region with ipsilateral cervical lymphadenopathy. Histologically characterized by prominent follicular hyperplasia, dense eosinophil infiltration, vascular proliferation, and fibrosis. Nephrotic syndrome (10-16%) may accompany. Although benign, recurrence rate is high (25-40%). On imaging, the triad of subcutaneous mass(es) + regional LAP + salivary gland involvement is characteristic.
Age Range
15-50
Peak Age
30
Gender
Male predominant
Prevalence
Rare
The exact etiology of Kimura disease is unknown, but excessive activation of Th2-mediated immune response is considered the fundamental mechanism. An unknown antigenic stimulus (parasitic infection, allergen, autoimmune trigger have been proposed) activates Th2 T cells leading to excessive production of cytokines such as IL-4, IL-5, IL-13. IL-5 increases eosinophil production in bone marrow causing peripheral eosinophilia; eosinophils migrate to the lesion creating dense tissue eosinophilia. IL-4 and IL-13 trigger B-cell IgE class switching causing elevated serum IgE. Vascular proliferation (capillary and HEV expansion) is related to release of VEGF and other angiogenic factors from eosinophil granules. On imaging, increased enhancement reflects this vascular proliferation. Fibrosis develops as chronic inflammation stimulates collagen deposition — reflected as signal decrease in fibrotic areas on T2. The growth mechanism of subcutaneous masses is the combination of chronic eosinophil infiltration + vascular proliferation + fibrosis. Renal involvement (nephrotic syndrome) likely results from eosinophil-derived cytokine damage to glomerular basement membrane — membranous nephropathy pattern is usually observed.
Subcutaneous mass in parotid/periauricular region, ipsilateral cervical LAP, and peripheral eosinophilia + elevated IgE in a young East Asian male is pathognomonic for Kimura disease.
On B-mode US, a well-defined or ill-defined, homogeneously hypoechoic subcutaneous mass is seen in the head-neck region. Concurrent cervical enlarged, hypoechoic lymph nodes are noted. Salivary gland (parotid or submandibular) may be diffusely enlarged and heterogeneous. Subcutaneous mass may show infiltration into surrounding fat tissue.
Report Sentence
On US, hypoechoic subcutaneous mass in head-neck region, ipsilateral cervical enlarged lymph nodes, and salivary gland enlargement are noted, consistent with Kimura disease.
On color Doppler, increased vascularity is seen in the subcutaneous mass — reflecting vascular proliferation triggered by eosinophil-derived VEGF. Hilar or mixed vascularity pattern may be seen in lymph nodes.
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Doppler demonstrates increased vascularity in the subcutaneous mass.
On contrast-enhanced CT, a well or ill-defined, homogeneously moderate to prominently enhancing subcutaneous mass is seen in the head-neck region. Concurrent cervical enlarged, homogeneously enhancing lymph nodes noted. Salivary gland enlargement and increased enhancement may accompany. Subcutaneous mass may show infiltration into surrounding soft tissues. Necrosis and calcification not expected.
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CT demonstrates enhancing subcutaneous mass in head-neck region, cervical enlarged lymph nodes, and salivary gland enlargement; consistent with Kimura disease.
On T2-weighted images, subcutaneous mass and lymph nodes show heterogeneous signal — inflammatory component hyperintense, fibrosis areas hypointense. As fibrosis proportion increases, T2 signal decrease becomes more prominent. Similar heterogeneous pattern seen in salivary gland involvement.
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On MRI T2, subcutaneous mass and lymph nodes demonstrate heterogeneous signal reflecting coexistence of hyperintense inflammatory and hypointense fibrotic areas.
On DWI, subcutaneous mass and lymph nodes may show mild diffusion restriction. ADC values generally in 1.0-1.5 × 10⁻³ mm²/s range. This mild restriction reflects cellular density of eosinophil and lymphoid infiltrate.
Report Sentence
On DWI, mild diffusion restriction is noted in the subcutaneous mass with ADC values (___×10⁻³ mm²/s) consistent with benign inflammatory process.
On FDG PET-CT, subcutaneous mass and enlarged lymph nodes demonstrate moderate FDG uptake (SUVmax generally 3-8). Increased uptake may also be seen in salivary gland involvement. Uptake is not as intense as lymphoma.
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FDG PET-CT demonstrates moderate FDG uptake (SUVmax: ___) in subcutaneous mass and enlarged lymph nodes; findings consistent with Kimura disease.
Criteria
Parotid/periauricular/submandibular subcutaneous mass + cervical LAP. Most common form (80%+).
Distinct Features
Typical subcutaneous mass + LAP triad on US and CT. Eosinophilia and elevated IgE strongly support diagnosis.
Criteria
Head-neck involvement + nephrotic syndrome (10-16%). Usually membranous nephropathy.
Distinct Features
Proteinuria, hypoalbuminemia, edema accompany. Membranous nephropathy or minimal change disease on renal biopsy. Steroid therapy may improve both LAP and renal involvement.
Criteria
Only lymphadenopathy without subcutaneous mass. Rare (5-10%). Eosinophilia and elevated IgE still accompany.
Distinct Features
Nonspecific LAP on imaging — differentiation from other causes of eosinophilia (lymphoma, parasitosis, allergy) needed. Diagnosis by biopsy.
Distinguishing Feature
Subcutaneous mass more rare in NHL and usually single dominant mass; in Kimura subcutaneous mass + LAP + salivary gland involvement triad is characteristic. Eosinophilia and elevated IgE not expected in NHL (except Hodgkin).
Distinguishing Feature
In IgG4-RD multiorgan involvement (pancreas, retroperitoneum) accompanies and serum IgG4 elevated; in Kimura involvement localized to head-neck and eosinophilia + elevated IgE predominate. IgG4-RD in older males, Kimura in young males.
Distinguishing Feature
Subcutaneous mass does not accompany reactive LAP and eosinophilia/elevated IgE not expected. In reactive LAP nodes are generally smaller, oval-shaped with preserved hilum.
Distinguishing Feature
In TB lymphadenitis rim enhancement and central necrosis predominate; in Kimura necrosis not expected and enhancement is homogeneous. Subcutaneous mass more rare in TB and skin fistulae (scrofuloderma) may be seen.
Urgency
routineManagement
medicalBiopsy
NeededFollow-up
6-monthKimura disease diagnosis is confirmed by excisional biopsy — demonstrating follicular hyperplasia, dense eosinophil infiltration, vascular proliferation, and fibrosis. First-line treatment is surgical excision or steroids. Steroids provide rapid response but recurrence is common when discontinued (25-40%). Recurrence is also high after surgery. Low-dose radiotherapy (25-30 Gy) may be effective. Steroid therapy is priority in nephrotic syndrome. Eosinophil count and IgE level used for disease activity monitoring. Malignant transformation has not been reported — prognosis is excellent but recurrence affects quality of life.
Kimura disease is benign but chronic and recurrence-prone. Surgical excision frequently recurs (25-60%). Corticosteroids are effective but relapse occurs upon dose reduction. Radiation therapy may be used in refractory cases. Development of nephrotic syndrome is an important complication requiring renal monitoring. Malignant transformation has not been reported.