Indian Journal of Dermatopathology and Diagnostic Dermatology

: 2020  |  Volume : 7  |  Issue : 1  |  Page : 42--43

A challenging case of clear cell hidradenoma of thumb

Hemant Kumar Sharma1, Shivani Prashar2,  
1 Department of Pathology, 158 Base Hospital, Bagdogra, Dist Darjeeling, West Bengal, India
2 Department of Medical Officer, 158 Base Hospital, Bagdogra, Dist Darjeeling, West Bengal, India

Correspondence Address:
Hemant Kumar Sharma
Department of Pathology, 158 Base Hospital, Bagdogra, Dist Darjeeling, West Bengal

How to cite this article:
Sharma HK, Prashar S. A challenging case of clear cell hidradenoma of thumb.Indian J Dermatopathol Diagn Dermatol 2020;7:42-43

How to cite this URL:
Sharma HK, Prashar S. A challenging case of clear cell hidradenoma of thumb. Indian J Dermatopathol Diagn Dermatol [serial online] 2020 [cited 2021 Jul 23 ];7:42-43
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Clear cell hidradenoma (CCH), a variant of hidradenoma, is a rare benign tumor of the distal excretory duct of eccrine sweat glands more commonly seen in adult females between the third and eighth decades of life. Usually, it is seen on the scalp, face, and trunk and extremely rarely in the breast and digital extremities. Clinically, it presents as a solitary, well-defined, unencapsulated, slowly growing intradermal tumor measuring 0.5–2.0 cm in size (maximum up to 10 cm) with extension to the subcutis.[1],[2],[3] Treatment is wide surgical excision with clear margins, but it may recur. Long-standing CCH rarely shows aggressive clinical behavior and malignant transformation resembling other clear cell malignancies such as metastasis of renal cell carcinoma (RCC).[4]

A 26-year-old male presented with a history of gradually progressive nontender nodular swelling over a proximal phalanx of the right thumb for the past 6 months. Local examination revealed a single firm to hard, mobile, subcutaneous swelling over the plantar aspect measuring 2.5 cm × 1.5 cm. No other relevant medical history was observed. Based on these findings, a clinical diagnosis of ganglion cyst was made, and excision of swelling was performed under local anesthesia. Macroscopic examination of the tissue revealed a single skin-lined grayish-white tissue firm bit measuring 2.0 cm × 1.5 cm × 0.8 cm. Microscopic examination revealed a well-circumscribed, lobulated tumor in the dermis with scalloped borders comprising solid cystic areas separated by thin vascular connective tissue stroma and extending up to subcutaneous tissue. Solid cystic areas were made up of two cell types: large round clear cells with eccentric dark nuclei in the center and elongated, polyhedral eosinophilic epidermoid cells with round-to-oval nuclei and small prominent nucleoli at the periphery. At some places, epidermoid cells were seen radiating from a centrally situated, thin-walled, dilated blood vessel surrounded by a broad zone of the acellular hyalinized amorphous stroma. No necrosis or mitotic activity is seen. Epidermis overlying the lesion was unremarkable [Figure 1], [Figure 2], [Figure 3]b. Based on histomorphology, a diagnosis of CCH was offered. The patient was kept on limited follow-up and did not report any recurrence so far.{Figure 1}{Figure 2}{Figure 3}

CCHs are traditionally thought to arise from distal excretory ducts of eccrine sweat glands based on enzyme histochemistry and electron microscopic features such as microvillus processes, abundant glycogen granules, and numerous mitochondria.[1],[3] Biopsy and immunohistochemical staining are usually necessary for differentiation and confirmation of diagnosis. Genetic studies of CCH showed chromosomal translocation in the form of t(11;19)(q21;p13) translocation-associated CRTC1-MAML2 gene fusion transcript similar to that seen in mucoepidermoid carcinoma and benign Warthin's tumor, indicating that these tumors evolve through activation of the same molecular pathway.[5] The main differential diagnosis includes metastatic RCC and other cutaneous malignancies with clear cell differentiation. Clinical indicators for a malignant change in long-standing CCH are the development of brown, blue, or red skin discoloration, skin thickening, skin erosion and ulceration, serous discharge, or tenderness.[1],[4] Treatment options for both benign and malignant CCHs are wide surgical excision with adequate margins to minimize the risk of recurrence due to tumor remnants followed by histologic confirmation of the adequacy of excision and follow-up. We report this case due to its rarity of occurrence on thumb and to increase awareness among clinical fraternity about keeping CCH in differential diagnosis during evaluation of clear cell lesions of digital extremitis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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