What is the black spot that suddenly grew on my finger

If black spots suddenly appear on your fingers, it may be a melanocytic nevus, which is a common skin condition. It may be shallow or may reach the dermis of the skin. Generally speaking, this type of melanocytic nevus will not cause adverse effects on your health. However, in life, if this kind of melanocytic nevus suddenly grows significantly larger or becomes ulcerated, you should go to the hospital for examination in time.

What is the black spot on my finger?

Melanocytic nevi are formed by a group of benign melanocytes that gather at the junction of the epidermis and dermis. Melanocytes may be distributed in the lower reticular diemis, between collagen bundles, and around other skin appendages such as sweat glands, hair follicles, blood vessels, nerves, etc., and occasionally extend to subcutaneous fat.

Melanoma characteristics

It may appear flat, raised, warty, granular, or other shapes and may be brown, black, or blue in color. There are two types of melanocytic nevi: congenital and acquired.

Congenital moles are mostly present at birth or in the neonatal period, while acquired moles may appear after six months of age until old age.

Acquired moles are usually 0.1 to 0.6 cm in size and can be pathologically divided into three types: junctional nevus (nevus cells are confined to the junction of the epidermis and dermis, which are intraepidermal nevus), compound nevus (nevus cells are not only distributed in the epidermis, but also extend down to the dermis), and intradermal nevus (nevus cells are completely located in the dermis). The clinical appearance of a mole is also related to its pathological classification. Junctional nevi appear as flat brown to black spots that do not protrude from the skin surface. Compound nevi usually appear as brown raised papules or nodules. Intradermal nevi are larger and more raised, appearing as light brown or flesh-colored nodules, which are generally called "flesh nevi".

Classification of melanocytic nevus

Congenital melanocytic nevus can be found in 1% to 2% of newborns, but the incidence of giant congenital melanocytic nevus is less than one in 20,000 (foreign statistics). Clinically, melanocytic nevi can be divided into three types according to their size:

Small melanocytic nevi: less than two centimeters in size, preferably distributed on the lower body, upper back, shoulders, chest and proximal limbs.

Intermediate melanocytic nevus: The size ranges from 2 to 20 cm.

Giant melanocytic nevus: It is larger than 20 cm in size and is mainly distributed on the back half of the trunk. Some people may have it on the head or limbs. It may cover large areas of skin on the body. They are usually dark in color and lightly covered with hair, with satellite lesions scattered around the main mass.

Most congenital giant melanocytic nevi are benign, but congenital giant melanocytic nevi are usually more complicated than acquired giant melanocytic nevi. According to its growth pattern, it can be divided into three types:

Compound or intradermal nervus: most common.

Neural nervus: A neural tube or neuroma may be present in the structure and may look like a neurofibroma.

Blue nervus: the least common.