| Dermatopathology Case 114: click
This is a form of nevus which is usually
compound in type and consists of plump epithelioid cells and spindle
cells.
Clinically, this lesion usually occurs on the head and neck region and
presents as darkly pigmented papule or nodule.
The lesion is usually
characterized by a sharply-demarcated, wedge-shaped lesion with its base
in parallel with the epidermis and its apex oriented toward the
subcutaneous fat or deep reticular dermis.
Case images
There may be asymmetry, plump
but fairly regular nests of melanocytes in the dermis.
Cytologic atypia with some
nuclear pleomorphism and a small to medium-sized eosinophilic nucleolus
is present.
There is absence of maturation
of cells.
Mitotic
activity is low. No atypical mitotic figures are present. There
may be occasional presence of normal dermal mitoses.
Patchy mononuclear inflammatory
cellular infiltrate is evident.
Although unusual, such
histologic features should not be regarded as a sign of malignancy in
deep penetrating
nevi.
The cells surround hair follicle, sweat glands and
nerves.
Pilar muscles are some times infitrated.
Many authors regard this lesion as a variant of
blue naevus.
The relevant differential diagnosis include melanoma :
1.Melanoma of the thickness of deep penetrating naevus usually displays
marked cellular and architectural atypia.
2. In deep penetrating naevus there is no pagetoid intraepidermal
spread.
3. There is no irregular epidermal acanthosis or thinning
4. No irregular fibroinflammatory dermal response is seen in deep
penetrating naevus.
5. Proliferating cell nuclear antigen (PCNA) is present in scattered
melanocytes (less than 5%) in the deep penetrating nevus. In melanoma
25%-75% cells show immunopositivity with PCNA.
Case
Links:
Case1
;
Case
2 |