Remote Possibility of Post Aural Swelling as Nodular Hidradenoma: A Case Report

Abstract

A 30-year-old female patient presented with swelling over the left post aural region of 6 months duration which gradually increased in size. Cutaneous examination: A solitary, non-tender, mobile swelling of variable consistency over the post aural region. Dermoscopic examination: Revealed white and red areas. Diagnosis of nodular hidradenoma was made by histopathological examination.

Introduction

Nodular hidradenoma or eccrine acrospiroma are benign tumours that arise from the eccrine sweat glands, which is more common in adults than in children. [1–3] It is usually solitary, slow growing, well circumscribed, freely mobile, firm, non tender, dermal lesion of varying size. The clinical diagnosis is based on the histopathology and the lesion is rarely subjected to FNAC [1–8]. Nodular hidradenoma are most commonly seen on the scalp, neck, trunk and extremities. It has been referred to as clear cell myoepithelioma, clear cell hidradenoma, eccrine sweat gland adenoma of the clear cell type, solid cystic hidradenoma and eccrine acrospiroma. [9–13]. It can mimic malignancy, if it gets ulcerated.

Case Description

: 30 year old female presented with complaints of swelling in the left post auricular region for 6 months, which started as a small solitary papule with insidious onset, gradually progressive and attained the present size which is 3*3 cm. No history of trauma/ pain /discharge from the swelling. No history of loss of weight or appetite. Pt was planned for excisional biopsy. Fine needle aspiration cytology showed a smear which was paucicellular with few lymphocytes and neutrophils in a hemorrhagic background [4–7].

Under local anaesthesia, patient in supine position with head turned to right, painting and draping was done. Infiltration with lignocaine was given around the post aural region; in toto excision was done and sent for histopathological examination which showed orthokeratotic stratified squamous epithelium with atrophy in focal areas. The underlying dermis showed an unencapsulated neoplasm arranged in lobules, strand formation, tubules with epidermoid extension. The cells are round to oval with moderate eosinophilic to vacuolated cytoplasm, round vesicular nucleus with nucleoli seen surrounded by cystic spaces in focal areas. The lumen of the cyst showed eosinophilic secretions admixed with pigment laden macrophages and areas of hemorrhage (Figs. 1, 2, 3, 4, 5).

Fig. 1.

Pre-operative

Fig. 2.

Intra-operative, aspiration of fluid from the cystic mass.

Fig. 3.

Excised mass.

Fig. 4.

Post –Operative, in follow up.

Fig. 5.

HPE.

Impression

Nodular hidradenoma.

Discussion

Nodular hidradenoma is a benign neoplasm of appendageal structures of dermis, namely apocrine gland. The tumors present as intradermal nodules and in most instances measure between 0.5 and 2.0 cm in diameter, although they may be larger. They are usually covered by intact skin, but some tumors show superficial ulceration and discharge serous material [12]. Although the tumor rarely gives the impression of being cystic clinically, gross examination of the specimen often reveals the presence of cysts [11, 13]. It exhibits eccrine differentiation on the basis of its enzyme histochemical and electron microscopic features [14]. The tumor is usually solitary; however, on rare occasions, multiple lesions have been reported [14].

Histopathologically, the tumor is well-circumscribed and may appear encapsulated. It is composed of epithelial lobules located in the dermis, which may extend into the subcutaneous fat. [12]. The tubular lumina are lined by cuboidal ductal cells or by columnar secretory cells. Occasionally, the secretory cells show active secretion suggestive of decapitation secretion [11, 14]. The wide cystic spaces are only rarely lined by a single row of luminal cells; more frequently, they are bordered by tumor cells that show no particular orientation and occasionally show degenerative changes [11]. This suggests that the cystic spaces may result from tumor cell degeneration.

Differential Diagnosis

1. 1. Trichilemmoma. This tumor shows peripheral palisading of its tumor cells whereas nodular hidradenoma commonly shows the presence of large cystic spaces and of tubular lumina, although nodular hidradenoma shares with trichilemmoma the presence of clear cells rich in glycogen and foci of keratinisation .

2. 2. Spiradenomas. Although the spiradenoma may present as dense dermal nodules akin to nodular hidradenoma clinically, it differs histopathologically from the latter by lacking large cystic spaces and will demonstrate hyalinized pink material, along with fewer ducts.

The primary treatment for nodular hidradenoma is complete excision; though, it can recur after local excision. Difficulty in histopathological interpretation is encountered in recurrence, when there is associated distortion and fibrosis and the histology of the primary lesion is unknown or unavailable. There have been several cases of low-grade atypical hidradenoma that have metastasised to lymph nodes with subsequent indolent behaviour following lymph node resection; the long-term natural history of these “benign metastases” is unknown [15].

Conclusion

This case is reported to emphasise the importance of histopathological examination in post aural swelling, as nodular hidradenoma is also a remote possibility. Even though, there is acute chance for recurrence, this should be followed up as there is also risk of malignancy.

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Conflict of Interest

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