Angiolymphoid hyperplasia with eosinophilia with follicular mucinosis.

Follicular mucinosis occurring along with angiolymphoid hyperplasia with eosinophils (ALHE) has been described in a 49-year-old male. The patient presented with pruritic hyperpigmented papules and nodules on the vertex and right parietal scalp. There was no any other complaint. Histopathological examination from one of the papule showed prominent blood vessels in the dermis lined by plump histiocytoid endothelial cells that were surrounded by a dense lymphoid infiltrate with numerous eosinophils; these findings are typical of angiolymphoid hyperplasia with eosinophilia. Features of follicular mucinosis were observed in the same section with 3 hyperplastic follicular infundibula containing pools of mucin in the infundibular epithelium. The concurrent occurrence of these 2 distinct histopathological patterns in the same biopsy specimen has been reported rarely.

What was known?

Follicular mucinosis has been described with many other conditions apart from alopecia mucinosa.

Introduction

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare, benign disease with distinctive histopathological features. Follicular mucinosis is not a distinct clinical entity, but it is a histopathological reaction pattern that has been described with many conditions apart from alopecia mucinosa. Concurrent occurrence of follicular mucinosis and ALHE is rare.[12]

In this case, we describe a 49-year-old Indian male with both these histopathological findings present in the same biopsy specimen leading to diagnostic dilemma.

Case Report

A 49-year-old married Indian male presented with multiple, pruritic hyper-pigmented papular lesions of 0.5-1 cm in size [Figure 1] over the vertex and right parietal scalp for a duration of 1 year. There was no history of preceding trauma or surgery at the site. The lesions arose spontaneously with gradual increase in size and number. There was no history of bleeding, but the patient complained of occasional pruritus in the lesions. There was no other relevant medical history. Peripheral blood eosinophilia was not present.

Figure 1

Multiple hyper-pigmented papules over scalp

A clinical differential diagnosis of prurigo nodularis and angiolymphoid hyperplasia with eosinophilia was considered.

Histopathological examination from a papule revealed normal epidermis with large, thick-walled vessels in the upper and mid dermis lined by plump endothelial cells protruding into the lumen. There was a dense lymphocytic infiltrate along with many eosinophils present in the perivascular area and other parts of the dermis. These features were consistent with angiolymphoid hyperplasia. In addition to these, there were several hyperplastic follicles showing plenty of bluish-gray stringy mucin collected in large pools within the follicular epithelium. [Figures 2 and 3] Alcian blue stain at pH 2.5 confirmed presence of mucin within dilated follicular infundibula, interstitium, and perivascularly. [Figure 4] Based on clinico-pathological correlation, a final diagnosis of angiolymphoid hyperplasia with eosinophilia with follicular mucinosis was made. Patient was advised intralesional bleomycin therapy; however, he lost to follow-up.

Figure 2

Diffuse infiltrate in dermis with vascular proliferation and dilated follicles with bluish mucin are seen. (H and E, ×40)

Figure 3

Close-up view showing thick walled dilated vessel with plump hobnail endothelial cells and numerous eosinophils in infiltrate, also a dilated follicle with mucin is shown. (H and E, ×100)

Figure 4

Alcian blue stain showing bluish mucin deposition within dilated follicular infidibulum, interstitium and peri-vascularly (Alcian blue, ×100)

Discussion

ALHE was first described in 1969 by Wells and Whimster.[2] It is a well-established clinico-pathological entity presumed to arise due to the development of arterio-venous (A-V) shunts in the skin. Clinically, it presents with erythematous, pruritic papules and nodules of varying sizes, affecting most commonly scalp, ears, face, and the neck regions. Histopathologically, diagnostic feature is the thick-or thin-walled vascular structures lined by protruding “hobnail” endothelial cells and an accompanying lymphoid infiltrate with numerous eosinophils. The density of both the lymphoid cells and eosinophils is highly variable.[1]

Follicular mucinosis presents with solitary or grouped erythematous papules, nodules, or plaques that may be indurated. Histopathologically, there is varying amounts of mucin accumulates within the follicular infundibula and the outer root sheath epithelium, accompanied by perifollicular lympho-histiocytic infiltrate that may contain eosinophils and plasma cells. It is classified into 2 types, primary (idiopathic) and secondary variety. Primary form usually affects children and young adults and has a shorter duration with a benign course, while secondary form is more widespread and almost always a disease of adults. It has been associated with numerous benign and malignant conditions including lymphomas, of which majority are mycosis fungoides. Other associations include Hodgkin's disease, cutaneous B-cell lymphoma, syringolymphoid hyperplasia with cutaneous T-cell lymphoma, and inflammatory conditions like chronic discoid lupus erythematosus, alopecia areata, angiolymphoid hyperplasia, eosinophilic pustular folliculitis, spongitic dermatitis, lichen striatus, leprosy, sarcoidosis, and growths such as verrucae and melanocytic nevi.[13]

The concurrent occurrence of follicular mucinosis with angiolymphoid hyperplasia is unusual; to date, only few such cases have been described in the literature. Wolff, et al. reported a case of angiolymphoid hyperplasia with follicular mucinosis in 1978.[4]

Bovet and Delacretaz reported similar case in 1979.[5] Joshi R. reported a similar case in 2007, probably a first case of this rare association from India.[1] We report a second similar case from India.

Due to rare occurrence of this association of ALHE and follicular mucinosis, it is not clear whether such cases should be treated differently. It is important that both clinicians and pathologist are aware of this rare association to avoid misdiagnosis.

In conclusion, we report a case of rare association of ALHE with follicular mucinosis, which shows importance of clinico-pathological correlation.

What is new?

This case highlights a rare occurrence of follicular mucinosis with angiolymphoid hyperplasia.