Nodular hidradenoma: Case report and brief literature review

In this article, we present the case of a 42-year-old woman with an asymptomatic papulonodular lesion on her right forearm appearing approximately two years before. An excisional biopsy subsequently yielded a histological diagnosis of nodular hidradenoma (NH). This case highlights the clarity of the clinical, dermatoscopic and histopathological images. We also discuss the need to consider other differential diagnoses, some of which are malignant, such as hydroadenocarcinoma, basal cell carcinoma, and amelanotic melanoma. By sharing this case, we aim to contribute to the dermatological and pathological community's knowledge, promote discussion of diagnostic strategies, and emphasize the importance of interdisciplinary collaboration.

Nodular Hidradenoma With Atypical Features in a Young Patient: A Case Report

Eccrine acrospiromas, also known as hidradenomas, are rare benign tumors that develop from the eccrine sweat glands. Hidradenoma is a multilobular, nonencapsulated, well-circumscribed dermal nodule that may involve the epidermis and extend into the subcutaneous fat. The etiology and prevalence of nodular hidradenoma are not well defined, but it is noted that it can occur spontaneously or traumatically. A 22-year-old, medically healthy male patient presented to the Dermatology clinic with a painless, progressive scalp lesion that had been bleeding on manipulation for the previous three years. On examination, a solitary, non-tender, soft-to-firm, pedunculated red scalp mass with a smooth surface, measuring 2 x 2 x 3 cm, was found over the left occipital area, with mild tenderness on touching. Excision was performed and sent for histopathological examination, which showed an adnexal tumor with features consistent with nodular hidradenomas, such as the tumor involving deep and peripheral margins. In a focal area, the mitotic rate was up to 3/10 HPF (high-power field) and was associated with a focal area of necrosis, which are considered atypical features. The differential diagnosis includes hidradenocarcinoma, renal cell carcinoma, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, trichoblastoma, trichilemmoma, cystadenoma, syringoma, and sebaceous adenoma.

Ultrasound Features of Nodular Hidradenoma: A Case Series of 27 Patients

OBJECTIVE

The aim of this study was to systematically investigate the ultrasonographic features of nodular hidradenoma (NH).

METHODS

A retrospective analysis was used to systematically summarize the ultrasonographic data of 27 patients diagnosed with NH by surgical pathology, including 13 eccrine nodular hidradenomas (ENH) and 14 apocrine nodular hidradenomas (ANH).

RESULTS

All instances of NH presented as solitary, well-defined lesions that infiltrated the dermis and subcutaneous fat layer, characterized by a heterogeneous hypoechoic internal solid component on ultrasound imaging. Color Doppler ultrasound revealed blood flow signals of Grade 2 or higher within 74% (20/27) of the lesions. Solid + cystic (cystic >50%) NH (14/27, 51.4%) were typically large and predominantly had an oval shape (11/14, 78.5%). Their distinctive sonographic features included the presence of inner septa within the cystic area (8/14, 57.1%), "snow falling" sign (7/14, 50%), or "fluid-fluid level" sign (7/14, 50%). Solid + cystic (cystic ≤50%) NH exhibited a lobulated morphology in all instances (5/5, 100%). No inner septa, "snow falling" sign or "fluid-fluid level" sign was observed within the cystic regions. The solid NH (8/27, 29.7%) morphology predominantly featured lobulation (6 out of 8, 75%). Ultrasound analysis revealed distinct differences between ENH and ANH. ENH were more lobulated, while ANH were predominantly oval. ANH were mainly solid + cystic (cystic >50%), whereas ENH were mostly solid. Inner septa, "snow falling" sign, and "fluid-fluid level" sign frequencies were similar in both groups, correlating more with cystic-solid composition than pathological subtype.

CONCLUSIONS

Ultrasonographic features of lobulated morphology and the presence of inner septa, "snow falling" sign or "fluid-fluid level" sign in the cystic region provide strong support for the diagnosis of NH.

Two blue nodules on the right leg

Hidradenoma is an asymptomatic benign sweat gland tumour with apocrine or eccrine differentiation. The most common dermoscopic features are bluish or pinkish homogeneous areas, white structures and vascular structures such as arborizing telangiectasias and polymorphous atypical vessels, mimicking other malignant tumours such as basal cell carcinoma and melanoma. As this tumour is a great masquerader, one should keep in mind hidradenoma in the differential diagnosis, when a blue colour is seen on dermoscopy. Owing to the risk of hidradenocarcinoma development on a pre-existing hidradenoma, the management of this tumour is surgical excision.

Atypical Nodular Hidradenoma Versus Low-Grade Hidradenocarcinoma in a Young Female Patient: A Case Report and Review of Literature

The objective of this study was to discuss an unusual postauricular mass in a pediatric patient. This mass had a broad differential including congenital anomaly, neoplasm, infection, and lymphovascular malformation. Atypical nodular hidradenoma is a rare adnexal tumor that is difficult to differentiate from hidradenocarcinoma. It is a rare entity, but especially rare in the pediatric population. This study aims to provide guidance on diagnosing hidradenoma and distinguishing it from hidradenocarcinoma through case presentation with a review of the literature. The patient in this report underwent wide location resection with close surveillance and has been disease-free during follow-up.

Reddish multilobulated mass on the scalp in a 13-year-old girl

Nodular hidradenoma is a rare benign adnexal tumor that occurs as a solitary nodule with a predilection for the head, face, and upper extremities. We describe the case of nodular hidradenoma presenting as an expanding nodule on the scalp. This tumor is a simulator of malignant lesions on clinical and dermoscopic examination. Our case emphasizes the importance to identify this tumor as a differential for scalp lesions.

Dermatoscopy: an auxiliary resource for the diagnosis of poroid neoplasms

Poroid neoplasms are benign epithelial proliferations with eccrine sweat gland differentiation. They are a challenging diagnosis because of the clinical heterogeneity, being able to mimic several malignant neoplasms. They are classified into classic poroma, hidroacanthoma simplex, dermal duct tumor and poroid hidradenoma. Association of histological subtypes occurs in more than 25% of cases. We report a case of a combined poroid neoplasia of classical poroma and poroid hidradenoma, reviewing its dermatoscopic features.

Dermoscopy of Adnexal Tumors

Cutaneous adnexal tumors include lesions with apocrine, eccrine, follicular, sebaceous, and mixed differentiation. Most are benign and sporadic, although malignant forms are occasionally observed and some cases develop in the setting of inherited syndromes. These tumors often cause immense diagnostic difficulty. Dermoscopy is a noninvasive technique that has greatly improved the diagnostic accuracy of different skin lesions, including these tumors. We provide a review of the literature on the dermoscopic structures and patterns associated with adnexal tumors. Most patterns associated with this kind of tumor are nonspecific and are observed in other nonadnexal tumors, especially in basal cell carcinomas.

Sonographic Characteristics of Apocrine Nodular Hidradenoma of the Skin

Nodular hidradenomas are benign sweat gland-derived tumors that can produce clinical and dermatoscopic misdiagnoses. Histologically, these tumors can be classified into eccrine and apocrine subtypes. We present the sonographic characteristics of 6 cases of apocrine nodular hidradenomas, which, to our knowledge, is so far the largest series reported. A detailed sonographic analysis included layers, body location, shape, diameters, echostructure patterns, and vascularity. Two sonographic signs not previously reported in these or other common dermatologic lesions were detected: "snow falling" and "fluid-fluid level." The sonographic characteristics of apocrine nodular hidradenomas can support their earlier and more precise diagnosis.