Topographic dermoscopy refers to the region-specific application of dermoscopic examination, emphasizing the unique morphological patterns found across different anatomical sites. On facial skin, the dermoscopic assessment requires recognizing patterns influenced by the high density of pilosebaceous units and sun-induced changes, often presenting pseudonetworks and annular-granular structures. The ear, with its thin skin and sebaceous gland concentration, reveals specific vascular and follicular clues important in distinguishing benign from malignant lesions.
On the chest and back, where the skin is thicker and sun exposure varies, dermoscopy must account for irregular pigment distribution and architectural disorder, especially in large nevi or early melanomas. Limb lesions may show distinctive features due to mechanical friction, hair density, and vascular variations, demanding precise interpretation to identify atypical nevi or skin cancers.
Palmar and plantar dermoscopy highlights the parallel ridge pattern critical for melanoma diagnosis, contrasting with benign acral patterns like the parallel furrow or lattice-like structures. Scalp and hair disorders benefit from trichoscopy, where dermoscopic evaluation reveals specific signs such as yellow dots, broken hairs, or black dots, aiding in the diagnosis of alopecia areata, androgenetic alopecia, or tinea capitis.
In nail disorders, onychoscopy enables visualization of melanonychia, hemorrhages, and nail matrix changes, crucial for distinguishing subungual melanoma from benign causes like trauma or fungal infection. Mucosal dermoscopy, though technically challenging, provides diagnostic clues in pigmented lesions of the lips, genitalia, or oral mucosa, requiring adaptation to moist, non-keratinized surfaces.
Finally, ultraviolet dermoscopy reveals a unique application: scabies mites fluorescing bright green under UV light, enhancing detection when traditional visualization fails. Topographic dermoscopy thus demands both anatomical knowledge and technical adaptation to maximize diagnostic accuracy across diverse body sites.