Commentary

Kimura’s disease was first described in China, in 1937, by Kimm and Szeto, who called it an eosinophilic hyperplastic lymphogranuloma. ^[1] Kimura’s disease is a chronic inflammatory disorder of unknown etiology, considered by Kimura et al.[2] as an, ”abnormal granuloma, with proliferation of lymphoid tissue”. This condition was more widely known as Kimura’s disease after Kimura et al. reported similar lesions in Japan. ^[3] In 1959, lizuka named the disease after Kimura. ^[4]

Kimura’s disease is an uncommon chronic, benign, inflammatory condition of unknown etiology. It occurs endemically in Asia and sporadically in the West . It is a rare form of chronic inflammatory disorder involving the subcutaneous tissue, predominantly in the head and neck regions, and is frequently associated with lymphadenopathy and / or salivary gland enlargement. The nodular lesions are deep-seated in the subcutaneous tissue and may clinically mimic a neoplasm. As it often imitates neoplastic or inflammatory processes, physicians should be aware of its clinical presentations. ^[5],[6]

Kimura’s disease is most commonly seen in Chinese and Japanese males, in the second and third decades of their life. ^{[7],[8],[9],[10],[11]} This disease is also seen in children. ^[6] Sporadic cases have been reported in non-Asians. The major clinical manifestation of this disorder is a slowly enlarging subcutaneous mass, often in the head and neck area, and frequently associated with lymphadenopathy and / or salivary gland enlargement. ^[7] It is usually associated with peripheral and tissue eosinophilia, in combination with markedly increased serum IgE concentration. ^[8] It has a predilection for the scalp, the periauricular area ^[12] and the postauricular area. ^[5],[6] Infrequently, the axillary, inguinal, and epitrochlear lymph nodes are involved. ^[7],[10] In some cases, isolated lymphadenopathy is the only manifestation of the Kimura disease. ^[5],[6],[7] It may mimic an inflammatory or neoplastic lesion. ^{[7],[9],[10],[13]} The clinical triad of subcutaneous nodules found in the head or neck, prominent peripheral eosinophilia, and highly increased IgE concentrations, particularly seen in Asians, is highly suggestive of Kimura’s disease. ^[8]

Bilateral involvement is rare. In 2007, Viswanatha ^[5] was the first to report a case of Kimura’s disease presenting as bilateral postauricular masses. Hiwatashi et al.[9] have reported Kimura’s disease presenting as bilateral auricular masses. In 2005, Tseng et al. reported a rare case of Kimura’s disease presenting as bilateral parotid masses. ^[14] The only reported systemic manifestation is renal involvement leading to the nephrotic syndrome. ^{[7],[15],[16]}

Kimura’s disease is a distinct reactive process. Its etiology and pathogenesis are unclear. ^{[9],[12],[15],[16]} Among the possible causes that have been postulated are trauma, an abnormal autoimmune reaction, and an allergic reaction to a parasite, virus, fungus, or toxin. ^[7],[9] Disturbance in the normal rate of production of eosinophils and IgE is thought to be a product of interaction between types 1 and 2 T helper cells. The presence of peripheral eosinophilia and a raised Ig E suggests an abnormal T cell stimulation to a hypersensitive reaction. ^[7],[9],[16]

Kimura’s disease is a benign chronic disorder with an indolent clinical course that frequently waxes and wanes over time. ^[7] Left untreated, these masses tend to slowly enlarge, and they may eventually become disfiguring. Over the long term, the affected patients appear to do well, although about 10% develop a steroid-responsive nephrotic syndrome. ^[8]

The differential diagnosis of Kimura’s disease includes such entities as eosinophilic granuloma, Mikulicz’s disease, acute nonlymphocytic leukemia, Hodgkin’s disease, follicular lymphoma, angioimmunoblastic lymphadenopathy, and angiolymphoid hyperplasia with eosinophilia. ^[8] Despite its rarity, Kimura’s disease should be considered in the differential diagnosis of any lymphadenopathy that demonstrates a eosinophilic infiltrate and prominent follicular hyperplasia. As Kimura’s disease is a distinctive clinicopathological entity, with characteristic histological features, it is important to distinguish it from a drug reaction, hypersensitivity or response to infectious agents. ^[7]

The cytological features of Kimura’s disease are not specific. The spectrum of cytological features observed in Kimura’s disease on fine needle aspiration may be mimicked by a variety of lesions. ^[13] The diagnosis may be suggested by fine needle aspiration, but it is established with a biopsy. ^[10] Pathologically, nodular lesions usually affect the lymph nodes, although skin or salivary tissues are occasionally affected. The normal tissue architecture is usually preserved, but follicular hyperplasia of the lymphoid tissue, with infiltration of lymphocytes, histiocytes, and large numbers of eosinophils is typical. The germinal centers may be necrotic and feature central eosinophilic abscesses. ^[8]

Three major therapeutic options exist for Kimura’s disease. They are surgical excision, steroid therapy, and radiotherapy. ^[8] Complete surgical excision, whenever feasible, is the preferred treatment. ^{[8],[10],[12]} Resection may be effective in permanently eradicating a mass if the entire lesion can be removed, but complete resection can be difficult because of the diffuse nature of the disease. Local irradiation has also been shown to be effective in shrinking the lesion, but is not advocated in children. ^[8],[11] Radiotherapy may be considered for recurrent cases. ^[9] Systemic and intralesional corticosteroid therapy has been shown to reduce the size of lesions, but tumors tend to recur when steroids are discontinued. ^[7],[8],[11]

Recurrence is common with all the modalities of treatment. ^[6],[9] Although the disease is nonfatal and does not undergo malignant transformation, the high recurrence rate (15 – 40%) is a major concern. ^[13] The clinical course of Kimura’s disease is benign. Untreated, these masses tend to slowly enlarge and may eventually become disfiguring. ^[8] Long term, patients seem to do well, although about 10% may develop a steroid-responsive nephrotic syndrome. The only reported systemic manifestation is renal involvement, leading to the nephrotic syndrome. ^{[7],[15],[16]}

Although Kimura’s disease is an uncommon disorder, it should be considered in any patient who presents with a painless mass, in association with marked eosinophilia and an increased serum IgE level.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.76182