A hidradenoma is a benign cutaneous condition that primarily affects the skin on the cheek. It first appears as a small dark colored fluid-filled growth. The tumor originates in the epithelium, cells that line the surface layer of connective tissue and of the sweat glands. There are several types of hidradenomas that may develop anywhere on the body, such as an acrospiroma, a hidradenoma papilliferum, nodular hidradenomas, and a hidradenocarcinoma. Any quick-growing or new growth should always be evaluated by a physician to determine if further treatment is needed.
Clear cell hidradenomas are called acrospiromas or poromas. This growth comes from the most distal portion of the sweat gland. It is similar in appearance to a renal cell carcinoma. A biopsy of the acrospiroma is taken to ensure the tumor is benign, and treatment usually involves the surgical excision of the lump.
Nodular hidradenomas may be a sign of an underlying condition. The formation of these benign sweat gland tumors is one of the symptoms of eccrine acrospiroma. A single hidradenoma nodule may develop anywhere on the body, but is most likely to appear on the face, head, neck, legs, and arms. If the growth becomes unsightly, it may be surgically removed.
Unusual hidradenomas may appear on the genitals of females. A type of benign growth called hidradenoma papilliferum occurs on the labia majora of the vulva. It may be also be present on the interlabial folds. These hidradenomas are caused by a nodule of breast tissue that is ectopic, or located away from its normal anatomical location, and are often present at birth.
Rarely, a malignant hidradenoma or hidradenocarcinoma may arise from a sweat gland. This cancerous growth infiltrates the surrounding tissues, and may metastasize and reoccur after treatment has ended. Most commonly diagnosed in elderly men, it first appears as a slow growing mass that is firm to the touch. The growth may also spread into the underlying bone and tendons causing pain during movement.
Diagnosis of malignant hidradenomas is made after the evaluation of a biopsy in a laboratory. A carcinoma forming from the sweat gland often mimics the appearance of a benign hidradenoma. Frequently, the tumor will not have any obvious nuclear changes or require the involvement of blood vessels to continue to grow, making diagnosis of the tumor difficult. Some of these cancerous tumors develop from benign hidradenomas. Treatment for the malignant tumor usually requires the surgical excision of the growth, followed by chemotherapy and radiation if needed.