On the faceis a central body region of sense and is also very central in the expression of emotion among humans and among numerous other species., they are formed by melanin pigment arranged either around the openings of the crater-like infundibula or in infundibular epithelium. The center of the infundibulum appears hypopigmentedThis glossary term has not yet been described.. If infundibula contain keratinized material the hypopigmented center is seen as a yellow or orange clod. Circles may be brown, gray or black.
- Brown circlesThis glossary term has not yet been described.: solar lentigoThis glossary term has not yet been described. or flat seborrheic keratosisThis glossary term has not yet been described..
- Gray circles on facial lesions: melanomaThis glossary term has not yet been described. in situnot seen to be spreading from a localized position.
- Differential diagnoses: lichen planusThis glossary term has not yet been described.-like keratosis, pigmented actinic keratosisActinic keratosis (also called solar keratosis and senile keratosis; abbreviated as AK) is a pre-cancerous patch of thick, scaly, or crusty skin., in situ melanoma.
- On the trunk or the extremities the pattern of circles may be a variant of the reticular patternA lesion with a reticular pattern has typical pigment network throughout the entire lesion..
- Differential diagnoses: junctional Clark nevusThis glossary term has not yet been described., solar lentigo, dermatofibromaDermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma.