Combined Nevi

 May be more common on head and neck






Microscopic




• Lesion overall orderly, symmetric, and well circumscribed

• Most commonly: Compound/intradermal melanocytic nevus plus blue nevus

• Others types of combined nevi include compound or intradermal nevus plus pigmented spindle or spitzoid cells


Top Differential Diagnoses




• Blue nevus (common and cellular types)
image Composed of dendritic to spindled melanocytes and melanophages

image Cellular often shows deep extension into dermis/subcutaneous

• Deep penetrating nevus
image Wedge-shaped architecture

image Often deep extension into dermis/subcutaneous

image Junctional nests may be present

image Dermal component composed of epithelioid/spindled melanocytes in nests bordered by melanophages

image Nests/fascicles of cells may be centered around adnexal/neurovascular structures in dermis

image Occasionally, bulbous/pushing margin is present

• Congenital melanocytic nevus: Present at birth
image May extend deep into dermis or subcutaneous tissue

image May infiltrate arrector pili, adnexal structures, nerves

image Maturation with depth

image
Combined Nevus With Conventional and Blue Nevus Components
This is an example of a combined nevus of the most common type (i.e., composed of a conventional compound melanocytic nevus image and a blue nevus image). The lesion is symmetric and bland appearing.


image
Combined Nevus: Conventional and Spitz
This combined nevus has conventional nevomelanocytes image (small cells with oval to round nuclei, some in round nests) as well as larger cells with eosinophilic cytoplasm and larger nuclei (spitzoid cells image).

image
Differential Diagnosis: Spitz Nevus, Desmoplastic Type
The differential diagnosis of a combined nevus may include other less common nevi, such as a desmoplastic Spitz nevus. The cells are large with eosinophilic cytoplasm image. There are interspersed melanophages and a sclerotic stroma image.

image
Differential Diagnosis: Deep Penetrating Nevus
The differential diagnosis of a combined nevus can also include a deep penetrating nevus, shown here, with a nodular collection of finely pigmented spindled to epithelioid cells in fascicles with many interspersed melanophages image.


TERMINOLOGY


Synonyms




• Melanocytic nevus with phenotypic heterogeneity, clonal nevus, nevus with focal epithelioid component, combined Spitz nevus, inverted type A nevus


Definitions




• Presence of 2 or more distinct populations of melanocytes (i.e., type A melanocytic nevus cells and spindled or dendritic cells) or

• Presence of 2 or more types of melanocytic nevi (i.e., intradermal melanocytic and blue or Spitz)

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Combined Nevi
Premium Wordpress Themes by UFO Themes
%d bloggers like this: