Any type of rash on the genital area is cause for concern, especially when it comes to extramammary Paget's disease. That's because this disease -- which can clearly be seen on the top of the skin -- sometimes signals an underlying cancer. The skin lesions associated with extramammary Paget's are found most often on the vulva in females, near the scrotum and penis shaft in males, or near the anal area on either gender. The skin sores are usually itchy and scaly (like dry skin), but can become red and crusty over time. And, when a topical steroid cream fails to clear up the dry patches, it becomes obvious the sores aren't from eczema. Plus, the sores don't crop up overnight. In fact, these indicators of extramammary Paget's can take years to develop and the appearance of an underlying cancer can, too. In some cases there may be signs of extramammary Paget's for more than a decade before cancer develops [source: DermNetNZ].
So what does this have to do with apocrine sweat glands? Plenty. Turns out these glands, which are in high numbers in the genital region, have a direct link to extramammary Paget's disease [source: Mazoujian]. While only about 25 percent of the people who have extramammary Paget's disease will also develop cancer, those deadly cells will originate from one place: the apocrine sweat glands. Of those diagnosed with an underlying cancer, about half will die -- despite treatment [source: Sandhu]
The treatment for extramammary Paget's is surgical removal of the lesions and underlying tissue, which presents a problem if they've spread throughout the genital region. Unfortunately, despite surgery, extramammary Paget's often makes a comeback, so frequent check-ups are the norm [source: DermNetNZ]. And, this isn't the only type of cancer that originates in the sweat glands. There's another very rare but deadly form, and we'll share the details, next.