A Weeping Tumor in a Young Girl: An Unusual Presentation of Nodular Hidradenoma.

A 10-year-old girl presented with a swelling on her left thigh that was associated with dripping of serous fluid from the lesion. Based on histological features of the excised tumor, a diagnosis of nodular hidradenoma was made. Atypical features including large size of the tumor, location on the lower limb, a weeping presentation, and histological finding of a nodular hidradenoma with an unusually large cystic cavity discharging fluid prompted us to report the case.

What was known?

Nodular hidradenoma is a rare benign tumor of sweat gland origin.

Introduction

Hidradenomas are benign cutaneous tumors of sweat gland origin, with the clear cell type constituting the most frequent histologic variety.[1] Usually, they are diagnosed in the elderly population, the peak incidence being the fifth to sixth decade. We describe a young girl, in whom nodular hidradenoma developed at the age of 6 years. Hence, our case demonstrates that nodular hidradenoma is a rare differential diagnosis of skin tumors, even in the pediatric age group.

Case Report

A 10-year-old girl presented to us with a swelling on the left thigh, which had been progressively enlarging over the preceding 4 years. She complained of watery discharge from the lesion, for the past 3 months. There was no preceding history of trauma involving the affected area. The past and family history was unremarkable.

Cutaneous examination revealed a solitary erythematous dome-shaped, well-circumscribed tumor, measuring approximately 6 cm × 4.5 cm. The surface of the tumor was smooth [Figure 1]. It was firm to palpation with a cystic feel at places. There was spontaneous dripping of straw-colored serous fluid at the rate of 20–30 drops/min, the discharge accentuating on pressure. There was mild tenderness on palpation. Regional lymphadenopathy was absent. The girl was otherwise in good health. Routine laboratory investigations including serum biochemistry panel were within normal limits. Biochemical analysis of the serous fluid revealed glucose 25 mg/dl, protein 4 g/dl, sodium 131 mmol/l, and potassium 4.3 mmol/l, almost similar to that of serum, the low concentration of glucose compelling us to think of something else. The mass was excised. Histopathological examination showed a well-circumscribed tumor in the dermis. The tumor was composed of both solid and cystic portions. The solid portion was largely composed of a cell type having finely granular, faintly eosinophilic cytoplasm with a dark-colored round to oval nucleus. Ductal luminal structures were visible in areas [Figures 2-4]. Besides, a large cystic cavity was noted within the mass. The cyst was lined by a single layer of cuboidal epithelium without evidence of decapitation secretion [Figure 5]. No mitotic figures were noticed. Angiolymphatic invasion or extension to deeper structures was not present. Based on clinicopathological correlation, a diagnosis of nodular hidradenoma was made.

Figure 1

Solitary dome-shaped, well-circumscribed tumor over the left thigh

Figure 2

Photomicrograph showing a well-encapsulated mass composed of solid and cystic portions (H and E, ×40)

Figure 4

Photomicrograph showing clear cells in the center along with cystic spaces (H and E, ×400)

Figure 5

Note the large cystic cavity within the mass. The cyst is lined by a single layer of cuboidal epithelium. No evidence of decapitation secretion (H and E, ×400)

Photomicrograph showing a well-encapsulated mass with large cystic spaces within it. Note the granular and faintly eosinophilic cytoplasm surrounding a dark-colored nucleus. Ductal luminal structures can be appreciated (H and E, ×100)

Discussion

Clear cell hidradenoma or eccrine acrospiroma of the skin was first described by Liu, in 1949, as clear cell papillary carcinoma of the skin.[1] It was reported under various designations such as nodular hidradenoma, eccrine acrospiroma, solid-cystic hidradenoma, clear cell acrospiroma, clear cell myoepithelioma, and eccrine sweat gland adenoma.[2]

Clinically, nodular hidradenoma presents as a slow-growing, red-, blue-, or brown-colored solitary, 5–30 mm in size, freely mobile and firm nodule, with an occasional cystic appearance. These are most commonly found on the scalp, face, thorax, abdomen, and gluteal region.[3] This tumor is found mainly in adults and is excised more commonly in women than in men. Our patient was a young girl who presented with a gradually increasing swelling on the lower limb, a site that is unusual for the development of nodular hidradenoma. The onset of the lesion was at the age of 6 years. Literature search showed very few cases of nodular hidradenoma on the lower limb, that too in the pediatric age group. However, a case of nodular hidradenoma masquerading as umbilical polyp has been reported in a 1-year-old male child.[4] Other atypical sites of presentation include caruncle and oral cavity.[56]

Some tumors discharge serous material while others tend to ulcerate. Our patient complained of serous discharge from the lesion, for the preceding 3 months. Clinical differential diagnoses for our case were cutaneous lymphoma, dermatofibrosarcoma protuberans, epidermoid cyst, and sweat gland tumor. However, histology reliably excluded all the possibilities. The histopathological characteristics of a classical nodular hidradenoma are distinct. It is well circumscribed and often encapsulated. The mass contains a mixture of solid and cystic areas in varying proportions. The solid portion is characterized by two types of cells. One cell type is polyhedral with a rounded nucleus and slightly basophilic cytoplasm. Another cell type is round and contains clear cytoplasm, containing glycogen. Clear cell change and/or squamous metaplasia may be prominent. Focal apocrine components may also be present.[2] Malignant transformation with metastasis has been reported.[78] Our case was characterized by unusual histological features. It was predominantly composed of a cell type having finely granular, faintly eosinophilic cytoplasm with a dark-colored round to oval nucleus. In addition to this, a large cystic cavity was seen. The chronically discharging nature of the tumor in our patient was attributable to the fluid-filled cavity within the lesion. Biochemical analysis of the fluid was almost consistent with that of serum, however, the low concentration of glucose hinted that it might be normal sweat. Recently, nuclear grooving has been described as a useful morphological feature to aid in its diagnosis.[9] Immunohistochemical staining of the tumor cells demonstrates positive staining with antibodies against CK-CAM 5.2, BER-EP4, p63, epithelial membrane antigen, S-100 protein, smooth muscle actin, and vimentin.[4] However, due to unavailability of resources and financial constraints, the immunohistochemical analysis could not be performed in our case.

The high rate of local recurrence (10%) and potential for malignant transformation make surgical removal with wide margins as the widely accepted modality of treatment.[1011] The high recurrence is attributable to incomplete resection and to tumor tissue located between the dermis and subcutaneous tissue. Malignant tumors usually develop as a de novo lesion. These are characterized by increased mitotic activity, angiolymphatic invasion, local extension into deeper tissues, and a dispersed pattern of growth.[12] Malignant lesions have been excised using Mohs micrographic surgery.[13] Radiation and chemotherapy have not shown to be of benefit.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

What is new?

Nodular hidradenoma in the pediatric age group is extremely rare

It is usually located over the head, neck, and trunk. In our case, the lesion was present in the lower limb

The presence of an unusually large cystic cavity within the tumoral mass, leading to serous discharge, makes our case even more interesting.