Compound melanocytic nevus
LEGEND
Benign symmetric melanocytic lesion with both epidermal and dermal components
There are several variants of benign melanocytic nevi: junctional, compound, intradermal, congenital, acral, etc.
The epidermis is highly variable: atrophic, hyperplastic, papillomatous +/- horn cysts
Multinucleated giant melanocytic cells may sometimes be observed
The principle of maturation, which is a reassuring feature in a nevus, refers to the progression of melanocytes from type A to type B to type C with increasing depth. In addition, melanocytes should lose their ability to produce pigment with depth.
There are three major types of melanocytic cells that may be found alone or in combination:
Type A: Epithelioid (large pale nucleus with abundant cytoplasm); typically found at the dermoepidermal junction and in the superficial dermis
Type B: Resembling lymphocytes (small hyperchromatic nucleus, scant cytoplasm); typically located in the mid-dermis
Type C: Neurocytic (spindle-shaped nucleus, pink cytoplasm); typically found in the deep dermis
Compound melanocytic nevus
LEGEND
Absence of pagetoid ascent, absence of atypia, and normal maturation
Absence of inflammatory infiltrate, unless irritated
Grouping of melanocytic cells into nests (theques) in the epidermis and dermis. These are monomorphic without atypia.
- Intraepidermal component: nested and/or lentiginous
Presence of melanophages in the dermis
Compound melanocytic nevus
LEGEND
Grouping of melanocytic cells in the dermis. These are monomorphic without atypia. Normal maturation is observed.
- Here is another example of a compound melanocytic nevus with a reticulated epidermis and several horn cysts.
