A "regular" stance indicates the left foot leading on the board with the right foot pushing, while a "Goofy" stance leads with the right foot on the board, pushing with the left. Professionals seem to be evenly distributed between the stances. Practice can yield a high level of ambidexterity between the two stances, such that even seasoned participants of a boardsport have difficulty discerning the footedness of an unfamiliar rider in action. To increase the difficulty, variety, and aesthetic value of tricks, riders can ride "switch stance" (abbreviated to "switch"). For example, a goofy-footed skateboarder normally performs an ollie with the right foot forward, but a "switch ollie" would have the rider standing with the left foot at the front of the board. In sports where switch riding is common and expected, like street skateboarding, riders have the goal of appearing natural at, and performing the same tricks in, both regular and goofy stances. Some sports like kitesurfing and windsurfing generally require the rider to be able to switch stance depending on the wind or travel direction rather than rider preference. Each time direction is changed, the stance changes. Snowboarders who ride switch may adopt a "duck stance", where the feet are mounted turned out, or pointed away from the mid-line of the body, typically at a roughly 15-degree angle. In this position, the rider will have the leading foot facing forward in either regular or switch stance. Switch, fakie and nollie
When a rider rolls backwards, this is called "riding fakie".
Lentigo maligna melanoma is a melanoma that has evolved from a lentigo maligna,: 695  as seen as a lentigo maligna with melanoma cells invading below the boundaries of the epidermis. They are usually found on chronically sun damaged skin such as the face and the forearms of the elderly. Lentigo maligna is the non-invasive skin growth that some pathologists consider to be a melanoma-in-situ. A few pathologists do not consider lentigo maligna to be a melanoma at all, but a precursor to melanomas. Once a lentigo maligna becomes a lentigo maligna melanoma, it is treated as if it were an invasive melanoma. Presentation
An invasive tumor arising from a classical lentigo maligna. Usually a darkly pigmented raised papule or nodule, arising from a patch of irregularly pigmented flat brown to dark brown lesion of sun exposed skin of the face or arms in an elderly patient. Diagnosis
The first problem is difficulty. As lentigo malignas often present on severely sun damaged skin, it is frequently found amongst numerous pigmented lesions – thin seborrheic keratoses, lentigo senilis, lentigines. It is difficult to distinguish these lesions with the naked eye alone, and even with some difficulty using dermatoscopy. As the lentigo maligna is often very large, it often merges with, or encompasses other skin tumors – such as lentigines, melanocytic nevi, and seborrheic keratosis. The second difficulty   is the biopsy technique. Even though excisional biopsy (removing the entire lesion) is ideal, and advocated by pathologists, practical considerations may indicate that this should not be done.