Intradermal nevus

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Intradermal nevus
Diagnosis in short

Intradermal nevus. H&E stain.

Synonyms intradermal melanocytic nevus

LM nests of melanocytes in dermis (only), melanocytes "mature" with depth, usu. no mitoses (occ. superficial), no destruction of surrounding structures, no conspicuous nucleoli, no significant melanocyte enlargement
LM DDx malignant melanoma (nevoid), junctional nevus, compound nevus, dysplastic nevus, skin tag, mastocytosis
Gross pigment skin lesion, usu. small, regular border, no irregularity in pigmentation
Site skin - see melanocytic lesions and common nevus

Prevalence very common
Prognosis benign
Clin. DDx pigmented skin lesions
Treatment none required, may be excised for cosmetic reasons

Intradermal nevus (abbreviated IDN), also intradermal melanocytic nevus, is a common benign melanocytic lesion.

The intradermal nevus is in the large group common nevus. In common language, nevus is known as a mole.

In the oral cavity these are known as intramucosal nevi.

General

Clinical:

  • ABCD = asymmetric, borders (irregular), colour (black), diameter (large).

Microscopic

Features:

  • Symmetrical lesion.
  • "Matures" with depth.
    • Less cellular with depth.
    • Less nuclear atypia with depth.
    • Smaller cells with depth.
    • Smaller nests with depth.
  • Rare mitoses (superficial).
    • No deep mitoses.
  • No destruction of surrounding structures.
  • No nucleoli.
  • In the dermis only - key feature.
  • +/-Adipocytes - uncommon.[1]

DDx:

Images

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Skin, Left Alar Crease, Biopsy:
- Benign intradermal nevus.

Block letters

SKIN LESION, BACK, PUNCH BIOPSY: 
- BENIGN INTRADERMAL NEVUS.

Adipocytes present

SKIN LESION, BACK, PUNCH BIOPSY: 
- BENIGN INTRADERMAL NEVUS WITH MATURE ADIPOCYTES.

Clinically suspicious

SKIN LESION, LEFT UPPER ARM, PUNCH BIOPSY:
- BENIGN INTRADERMAL NEVUS, INCOMPLETELY EXCISED.

COMMENT:
HMB-45 marks very rare superficial cells. Ki-67 staining does not show apparent melanocyte
staining. MITF marks the melanocytes and demonstrates maturation of the melanocytes with depth.

Micro

The sections show melanocytes in the dermis separated from the epidermis by a Grenz zone. The lesion is symmetrical in its architecture and pigment distribution. Superficially, melanocytes are in nests. Melanocytes mature with depth. No mitotic activity is appreciated.

The lesion is completely excised in the plane of section.

IDN with congenital features

The sections show melanocytes in the dermis separated from the epidermis by a Grenz zone. The lesion is symmetrical in its architecture. Superficially, melanocytes are in nests. Melanocytes mature with depth and track along adnexal structures. No mitotic activity is appreciated. The lesion is incompletely excised in the plane of section.

See also

References

  1. Eng, W.; Cohen, PR. (Nov 1998). "Nevus with fat: clinical characteristics of 100 nevi containing mature adipose cells.". J Am Acad Dermatol 39 (5 Pt 1): 704-11. PMID 9810886.