Introduction:
Sweat glands in the body produce sweat in response to heat, stress, and exercise, which helps control the body temperature (thermoregulation). Our skin consists of two types of sweat glands, namely eccrine and apocrine. Eccrine sweat glands are distributed over the entire body surface except for the lips and some parts of the external genitalia. In eccrine sweat glands, the ducts open to the skin surface, and its secretion is watery in consistency.
Apocrine glands are another type of sweat gland that is seen around the armpits and perianal areas in the body. Ducts of apocrine sweat glands open into the hair follicles. Sweat gland carcinomas are rare malignant tumors of sweat glands. Eccrine carcinoma refers to the malignant tumors of eccrine sweat glands. It is a rare skin tumor.
This article emphasizes the causes, clinical features, staging, diagnosis, and management of eccrine carcinoma.
What Is Eccrine Carcinoma?
Eccrine carcinoma refers to cancer that originates from the eccrine sweat glands. It is a rare skin tumor that has the potential for metastasis and local destruction with a high recurrence rate. Clinically it is characterized by the presence of slow-growing nodules or plaques, mainly on the scalp, trunk, and other extremities. Eccrine carcinomas are often difficult to identify since they look morphologically similar to other common tumors and due to a lack of reliable immunohistochemical markers.
Some of the common types of eccrine carcinoma include porocarcinoma, hidradenocarcinoma, malignant spiradenoma carcinoma, malignant cylindroma, syringoid eccrine carcinoma, and microcystic adnexal carcinoma, mucinous carcinoma, adenoid cystic carcinoma, and ductal papillary adenocarcinoma.
What Causes Eccrine Carcinoma?
The exact cause of eccrine carcinoma is still unclear. However, some of the risk factors for eccrine carcinoma include
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Family history.
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Immunosuppression.
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Ultraviolet radiation.
Besides these risk factors, radiation therapy is a risk factor in certain cases of microcystic adnexal carcinoma development.
Who Is More Likely to Be Affected by Eccrine Carcinoma?
Eccrine carcinomas are more commonly seen in elderly patients in their sixth to eighth decades of life. Sex incidence is found to be equal for eccrine carcinoma. But certain types of malignant eccrine neoplasm, like malignant chondroid syringoma and primary cutaneous adenoid cystic eccrine carcinoma, are more common among females than males. The racial predisposition of microcystic adnexal carcinoma (MAC) was earlier found only in white patients. But Peterson et al. and Gardener et al. reported MAC in African Americans.
What Is the Clinical Presentation of Eccrine Carcinoma?
Clinically, eccrine carcinoma presents as a slow-growing, bluish, brown erythematous papule or nodule. Sometimes the lesion may ulcerate. It is more commonly seen on the head or extremities and less commonly seen in the trunks. It accounts for less than 0.01% of all diagnosed cutaneous malignancies. Some of the subtypes of eccrine carcinoma exhibit salient clinical features. It is as follows:
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Mucinous Eccrine Carcinoma: It presents clinically as a solitary asymptomatic skin-colored nodule with ulceration over the lesion at times. It is more commonly seen in the eyelids and the scalp.
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Hidradenocarcinoma: It is a malignant sweat gland tumor that clinically presents as a slow-growing solitary lesion on the head and neck skin. It tends to involve the nearby tissues or lymph nodes.
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Microcystic Adnexal Carcinoma (MAC): Clinically, it appears as an indurated plaque over the nasolabial area.
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Eccrine Porocarcinoma: It is more commonly seen on the legs and feet but also affects the trunk and head. Clinically, it appears as a red dome-shaped nodule with a shiny surface that tends to get ulcerated. Sometimes it can present clinically as a wart-like plaque.
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Syringoid Eccrine Carcinoma: It is commonly presented over the scalp as a tender nodule or plaque.
Eccrine carcinoma can lead to complications in response to any local invasion or metastasis. High recurrence rates are seen after surgical excision of the tumor. Multiple cutaneous metastatic deposits, along with visceral spread, are seen in cases of eccrine porocarcinoma.
How Is Eccrine Carcinoma Diagnosed?
A skin biopsy is the most commonly used diagnostic measure to diagnose eccrine carcinoma. A small amount of tissue is removed from the affected area and sent for pathological examination in a skin biopsy. It reveals the presence of any growth of new or abnormal tissue.
Immunohistochemistry is another procedure that helps in diagnosing eccrine carcinoma, but it is inconsistent. Eccrine carcinoma can be detected with the help of certain tumor markers like:
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CEA (carcinoembryonic antigen).
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Progesterone receptors.
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Estrogen receptors.
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Cytokeratin 5/6.
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Cytokeratin7.
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Epithelial membrane antigen.
What Are the Pathological Stages of Eccrine Carcinoma?
Eccrine carcinoma is staged pathologically as follows:
Primary Tumor (pT):
1) pTX: The primary tumor is not accessible.
2) pT0: No evidence of primary tumor.
3) pTis: Carcinoma in situ.
4) pT1: The size of the tumor is not more than 2 cm in dimension.
- pT1a: Tumor is 2 mm or less in thickness or is limited to the dermis.
- pT1b: Tumor is larger than 2 mm but not more than 6 mm in thickness and is limited to the dermis.
- pT1c: Tumor is more than 6 mm in thickness and/or invades the subcutis.
5) pT2: The size of the tumor is greater than 2 cm but not more than 5 cm.
- pT2a: The tumor is 2 mm or less in thickness or is limited to the dermis.
- pT2b: The tumor is more than 2 mm in thickness but not greater than 6 mm in thickness and is limited to the dermis.
- pT2c: The tumor is more than 6 mm in thickness and/or invades the subcutis.
6) pT3: Tumor more than 5 cm in dimension.
- pT3a: 2 mm or less in thickness or limited to the dermis.
- pT3b: Greater than 2 mm but not more than 6 mm in thickness and is limited to the dermis.
- pT3c: Greater than 6 mm in thickness and/or invading the subcutis.
7) pT4: Tumor invades deep extra dermal tissue (like cartilage, skeletal muscle, and bone).
- pT4a: The tumor is 6 mm or less in thickness.
- pT4b: The tumor is more than 6 mm in thickness.
Regional Lymph Nodes (pN):
- pNX: Regional lymph nodes are not accessible.
- pN0: There is no regional lymph node metastasis.
- pN1: Regional lymph node metastasis is present.
Distant Metastasis (pM):
- pMX: The presence of distant metastasis is not accessible.
- pM1: Distant metastasis is present.
How Is Eccrine Carcinoma Treated?
Consultations with surgical and medical oncologists and dermatologists are necessary for managing eccrine carcinoma. They devise the proper treatment approach based on the nature of eccrine carcinoma. For tumors with negative margins, the treatment of choice usually preferred is surgical excision. Wide excision of the lesion is recommended since the tumor is locally infiltrating and tends to invade the perineural. Surgical approaches like radical surgical excision and Mohs micrographic surgery are also used. A high recurrence rate is one of the most common complications of surgical excision. Mohs micrographic surgery shows decreased recurrence of lesions as compared to surgical excision.
For treating cases of eccrine carcinoma with distant metastasis, radiotherapy is used. The use of chemotherapy is not found to be successful in treating eccrine carcinoma.
What Are the Differential Diagnoses of Eccrine Carcinoma?
The differential diagnoses of eccrine carcinoma include:
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Cutaneous squamous cell carcinoma.
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Malignant melanoma.
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Dermatologic manifestations of Merkel cell carcinoma.
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Dermatologic manifestations of metastatic carcinomas.
Conclusion:
Eccrine carcinoma is a rare malignant skin tumor that originates in the eccrine sweat glands. It can potentially metastasize and lead to local destruction along with a high recurrence rate. In order to treat eccrine carcinoma, surgical excision is the preferred option, but mostly the lesion tends to recur after surgical excision. For treating cases of eccrine carcinoma with distant metastasis, radiotherapy is used. Consulting a dermatologist and medical and surgical oncologists will help more in understanding the condition.
