Angiolymphoid Hyperplasia With Eosinophilia 

Angiolymphoid hyperplasia with eosinophilia (ALHE) is an uncommon idiopathic condition that manifests in adults as isolated or grouped papules, plaques, or nodules in the skin of the head and neck. Most patients present with lesions in the periauricular region,^[1] forehead, or scalp. Rare sites of involvement include the hands,^[2] shoulders, breasts, penis, oral mucosa, and orbit.

A distinct pathologic entity, ALHE is marked by a proliferation of blood vessels with distinctive large endothelial cells. These blood vessels are accompanied by a characteristic inflammatory infiltrate that includes eosinophils. The lesion is benign but may be persistent and is difficult to eradicate. Whether ALHE represents a benign neoplasm or an unusual reaction to varied stimuli, including trauma, remains unclear.

While ALHE shows some similarity to Kimura disease, it is generally regarded as a separate entity.^{[3, 4]} While ALHE lesions are superficial, Kimura disease involves deeper tissues such as lymph nodes, salivary glands, and the subcutis. However, a 2006 report describes ALHE involving the nail bed and underlying bone.^[5] Further, no reports describe a patient with simultaneous tumors, one consistent with Kimura disease and one consistent with ALHE.^[6] Such findings challenge whether or not Kimura disease and ALHE represent a spectrum of the same disease.

Although ALHE may be a benign tumor, numerous factors suggest that it is an unusual reactive process. Approximately half the patients have multifocal lesions that are grouped anatomically. ALHE has occurred following various forms of trauma or infection. Histologically, most cases of ALHE show damaged and/or tortuous arteries and veins at the base of the lesion, suggesting that arteriovenous shunting may play a role in the pathogenesis. Hyperestrogenemia (eg, in pregnancy,^[7] with oral contraceptive use) may foster lesion growth. Additionally, the distinctive inflammatory infiltrate in ALHE appears to be an intrinsic (not secondary) component of the lesion. Approximately 20% of patients have blood eosinophilia. However, immunoglobulin E levels are not elevated.^[8]

Additionally, 3 reported cases describe follicular mucinosis and ALHE occurring in the same biopsy specimen.^[9] Interestingly, one report of monoclonality in a patient with ALHE who subsequently progressed to mycosis fungoides raises the question of whether or not ALHE could be an early form of T-cell lymphoma.^[10] It should be stressed that most cases are entirely benign.

Frequency

United States

Frequency in the United States is unknown. ALHE is uncommon but not rare.

International

Although frequency is unknown, cases have been reported worldwide. ALHE is uncommon but not rare; it may be more common in Japan than in other countries.

Mortality/Morbidity

ALHE can persist for years, but serious complications (eg, malignant transformation) do not occur. A few cases of nephropathy have been reported in patients with ALHE; however, the association is not strong. This is in contrast to the related entity, Kimura disease, for which the association with nephrotic syndrome is strong. Of note, although, coexistence of Kimura disease and ALHE in the same patient, along with minimal-change glomerulopathy, has been reported.^[11]

Race

ALHE is seen most commonly in Asians, followed by whites. Although less common, blacks can develop ALHE.

Sex

ALHE is slightly more common in females; however, a male predominance has been noted in selected Asian studies.

Age

ALHE presents most commonly in patients aged 20-50 years, with mean onset of 30-33 years. This condition is rare in elderly patients and in the non-Asian pediatric population.