Pathology of Hidradenocarcinoma

Dr Sampurna Roy MD                                    2022

Hidradenocarcinoma is a very rare sweat gland tumour with an incidence as low as 0.05% in the general population.

The tumour range from locally recurring, low grade well differentiated tumour to highly aggressive high grade tumour with potential for local and distant metastasis to lymphnodes, bones and lungs.

Site: Often located on the face, scalp and extremities as an ulcerated reddish nodule. It can also involve the eyelid, finger and the perianal region.

Age: In elderly patients and sometimes in children and at birth.

 

Microscopic features:  Based on histological classification, there are recognized variants including nodular hidradenocarcinoma, malignant acrospiroma, malignant clear cell hidradenomas and clear cell eccrine carcinoma. Characteristic features are as follows: Asymmetrical tumour ;  Infiltrative dermal proliferation of variable sized lobules and nests showing cyst formation ; Connection to the epidermis is rare ; Composed of a mixture of eosinophilic polygonal cells, squamous cells, mucinous and clear cells;  Pleomorphism and necrosis is common;  There are ducts and intracytoplasmic lumina; Decapitation secretion is present in some cases ; Glycogen is demonstrated in the cytoplasm of some of the clear cells.   Criteria of malignancy : -Infiltrative growth pattern. -Prominent cytological atypia. In some cases there is minimal atypia. -High mitotic activity (not reliable criteria) -Perineural invasion -Vascular invasion -Presence of comedonecrosis.

Differential diagnosis: 

Tumours composed of predominantly clear cells. Hidradenocarcinoma needs to be distinguished from metastatic clear cell carcinoma particularly renal cell carcinoma.

The standard of care for the treatment of localized HA usually includes wide local excision with clear margins.

The role of a sentinel lymph node biopsy is unclear.

In about 50% of moderately to poorly differentiated tumors, lymph node involvement has been reported. While regional lymph node dissection is usually performed in clinically positive lymph nodes, the role of adjuvant chemotherapy and radiotherapy is not established.