Kimura disease

Kimura disease is a rare benign inflammatory disease that characteristically manifests as enlargement of cervical lymph nodes and salivary glands.

Epidemiology

Kimura disease typically affects males (80%) in between 20 and 40 years of age (80% of cases) ^1-2, and is most frequently seen in Asia. Sporadic cases are seen in other geographic regions, however these are uncommon. An infectious agent is presumed to be the cause of an immunological response, however no specific pathogen has as yet been identified ^4-5.

Clinical presentation

Presentation is with subcutanous masses and enlargement of the lymph nodes of the head and neck, particularly near the angle of the mandible and post-auricular groups. Salivary glands (particularly the parotidand submandibularglands)  and lymph nodes of the axilla, groin, popliteal fossa, medial epicondyle ⁶ and elsewhere may also be involved ^1,4-5. They are usually not painful. Involvement of adjacent soft tissues is uncommon, although direct extension into the pinna of the ear has been described.

These changes are usually associated with eosinophilia in the peripheral blood and in tissues, and marked increase in serum levels of immunoglobulin E (IgE) ^4-5.

Pathology

Histologically Kimura disases is characterised by:

• proliferation of lymphoid follicles
• cellular infiltrates
  • eosinophils (majority), sometimes progressing to eosinophilic abscesses
  • also plasma cells lymphocytes, and mast cells
• vascular proliferation of post-capillary venules
• fibrosis

Peripheral eosinophilia is common.

Radiographic features

Ultrasound

Ultrasound is a useful modality for assessment of the neck and to aid in biopsy.sonographic features include ²:

• solid, enlarged nodes sometimes maintaining hilar architecture
• hypoechoic, usually homogeneous - 87: 87%
• foci of necrosis uncommon - 13: 13%
• increased vascularity usually in a hilar distribution - 87: 87%
• salivary glands also hypoechoic, but usually more heterogeneous

CT

CT demonstrates non-specific appearances consisting of:

• markedly enlarged cervical nodes +/- parotids and sub mandibular glands
• intense enhancement of nodes
• heterogenous enhancement of salivary glands

MRI

MRI signal intensity and enhancement varies depending on the amount of fibrosis and vascular proliferation present ¹.

• T1 -: hypointense or isointense compared with salivary tissue
• T2
  • typically hyperintense compared to salivary gland tissue
  • variable according to degree fibrosis
• T1 C+ (Gd): - usually usually homogeneous enhancement

Treatment and prognosis

Kimura disease is benign, and no firmly established treatment protocols have been described. Options include ^4-5:

• conservative management
• radiotherapy
• steroid and oxyphenbutazone (with only transient improvement)¹
• resection

Recurrence rate is high for steroids and surgery, and as such radiotherapy is favoured by some authors ⁴, although as the condition is benign and patients are young not all agree ¹.

EtymologyHistory and etymology

First described in China by Kim and Szeto in 1937 and then in 1948 by Kimura et al in Japan ⁵.

Differential diagnoses

Differential diagnosis on imaging is that of lymph node enlargement, and includes:

• benign reactive nodes / infectious/infectious mononucleosis / drug/drug reactions
• nodal metastases
• lymphoma / leukaemia /leukaemia
• tuberculous adenitis
• Kikuchi-Fujimoto disease
• Castleman disease
• parasitic infections

Histologically Kimura disease was initially thought to be related to angiolymphoid hyperplasia with eosinophilia (ALHE), however clinically and radiologically these two entities are clearly different:

• ALHE affects primarily female Caucasians
• ALHE involves dermis without lymph node enlargement