Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare benign vascular inflammatory lesion with a prominent proliferation of atypical endothelial cells and an infiltrate that contains numerous eosinophils5
. It was first described in 1969 by Wells and Whimster1
, who thought that Kimura's disease and ALHE represented two ends of the same disease spectrum, i.e., an initial marked vessel proliferation and later a lymphocyte proliferation. However, Rosai et al6
recognized that Kimura's disease and ALHE differed in terms of their histopathological features and they suggested that they are distinct entities. Therefore, they are now regarded as two distinct diseases7,8
Clinically, ALHE presents as single or multiple pink to reddish-brown papules or subcutaneous nodules that are usually located on the head and neck, and especially in the preauricular region, and ALHE generally occurs in young adults9
. It has been described less frequently at other sites10,11
and in children12,13
. Histopathologically, ALHE is characterized by the proliferation of blood vessels lined by plump epitheloid or histiocytoid endothelial cells that protrude into the lumen, and this occasionally results in a cobblestone appearance. The vascular proliferations are surrounded by a mixed inflammatory infiltrate that predominantly consists of eosinophils, but the infiltrate includes plasma cells and lymphocytes4,8
. By contrast, Kimura's disease is characterized by multiple lymphoid follicles with germinal centers and eosinophilic microabscesses ()8
Table 1 Comparison of the histological characteristics of angiolymphoid hyperplasia with eosinophilia and Kimura's disease4,7,8,10
In our case, the histology showed multiple lymphoid follicles without germinal centers in the dermis and subcutaneous tissue, there were atypical endothelial cells and positive staining for factor VIII-related antigen, which is all compatible with ALHE. The same as Helander et al14
reported, a diffuse T-cell and B-cell infiltration was observed in our case.
The pathogenesis of ALHE is unknown, with opinions varying between it being a benign vascular neoplasm to a reactive inflammatory lesion in the form of an atopic reaction to various agents or trauma. It has recently been considered a reactive inflammatory disease secondary to an immunological mechanism. This is supported by the immunoglobulin deposition within blood vessels, the increased serum cryoglobulin levels, the blood and tissue eosinophilia, the elevated serum IgE concentrations and the slight predominance in atopic patients15
Our patient is of interest because of the unusual site and his young age. The development in a child, the atypical location on the right upper arm and the remarkable correlation between the injection site and the location of the lesion suggests an etiological role for vaccination. We hypothesize that a persistent inflammatory response secondary to damage to vessels, or a vaccination or immunological reaction or both are most likely involved in the development of ALHE in our patient. Although it is difficult to demonstrate a direct etiological role for vaccination in the development of ALHE, vaccination may be one of multiple factors that promote an inflammatory reaction and vascular proliferation that can result in the development of ALHE.
The treatment of choice for ALHE is complete surgical excision, although recurrences are common16
. Therefore, in a child, ALHE must be included in the differential diagnosis of nodular lesions that occur at vaccination sites such as the arms and thighs.