Eccrine spiradenomas are uncommon benign tumors of the skin. Most often they are solitary, but they can occur in conjunction with cylindromas in the Brooke-Spiegler syndrome. They can occur in any location on the human body but are most commonly found on the head and neck. The next most common region is the ventral trunk. These tumors are uncommon on the extremities. Spiradenomas tend to appear between the ages of 15 and 40 years, although they have been reported to occur at any age. Malignant degeneration is extremely rare, but if it does occur, it is often fatal.
Clinical Findings: A spiradenoma usually manifests as a solitary dermal nodule or papule ranging from 5 to 20 mm in diameter. The average size is approximately 10 mm. They are typically seated deeply in the dermis and can be very painful to light touch. The tumors grow very slowly, and except for the pain can go unnoticed for some time. The pain tends to have a waxing and waning course, and it is more often than not the reason the patient seeks medical advice. The overlying epidermis is almost always normal. The dermal nodule sometimes takes on a purple or bluish coloration. Although they are most commonly solitary, multiple spiradenomas may be seen in association with multiple cylindromas in Brooke-Spiegler syndrome.
Brooke-Spiegler syndrome is an autosomal dominant inherited skin condition caused by a genetic defect in the CYLD gene. This syndrome is characterized by multiple cylindromas, spiradenomas, and trichoepitheliomas. The tumors usually begin in the third decade of life and increase in number and size throughout the patient’s life. The CYLD gene encodes a tumor suppressor protein and is an important downregulator of the nuclear factor NF-κB pathway. The clinical phenotype varies depending on the type of mutation in this gene. Patients with familial cylindromatosis also have defects in this gene. The gene has been localized to the long arm of chromosome 16.
The eccrine spiradenoma is considered to be one of the group of unique tumors that can cause painful dermal nodules. This group also includes angiolipomas, neuromas, glomus tumors, and leiomyomas. This group of tumors makes up the differential diagnosis when evaluating these painful nodules. If the nodule is asymptomatic, lipoma and other adnexal tumors would also be considered in the differential diagnosis.
The exact cell type from which the spiradenomas are derived is still undetermined. They were originally believed to arise from eccrine tissue, but increasing evidence is pointing to a derivation from apocrine tissue.
Histology: The histological hallmark of an eccrine spiradenoma is the appearance of large nests of basophilic cells in the dermis. There are no epidermal changes, and the multilobulated tumors do not connect with the epidermis. This gives rise to the term “blue balls in the dermis.” The tumor is composed of two unique cell types. Large, pale cells predominate, with surrounding aggregates of smaller basophilic cells that contain hyperchromatic nuclei. The tumor is well circumscribed and is surrounded by a fibrous capsule.
Treatment: Surgical excision is curative. Surgical removal with carbon dioxide laser ablation has also been found to be highly successful. Because of the number and size of the tumors in patients with the Brooke Spiegler syndrome, a multidisciplinary approach is often taken. Plastic surgeons are often the primary physicians removing these tumors.