Dark skin focalities

Author: Mikael Häggström

Dark skin focalities (in this case, from top left and clockwise: Spitz nevus, seborrheic keratosis, elevated melanocytic nevus and melanoma)

Skin with one or more areas that are darker than the surroundings. They are part of suspected malignant skin excisions.

Fixation

Generally 10% neutral buffered formalin.

  See also: General notes on fixation

Gross processing of skin excisions

Gross pathologic processing of skin excisions

	Lesion size
	<4 mm	4 - 8 mm	9 - 15 mm
Benign appearance	File:Tissue selection from skin excision with lesion less than 4 mm with benign appearance.png	File:Tissue selection from skin excision with lesion 4-8 mm with benign appearance.png	File:Tissue selection from skin excision with lesion 9-15 mm with benign appearance.png
Suspected malignancy	File:Tissue selection from skin excision less than 4 mm with suspected malignant lesion.png	File:Tissue selection from skin excision 4-8 mm with suspected malignant lesion.png	File:Tissue selection from skin excision 9-15 mm with suspected malignant lesion.png

In table above, each top image shows recommended lines for cutting out slices to be submitted for further processing. Bottom image shows which side of the slice that should be put to microtomy. Dashed lines here mean that either side could be used. Further information: Gross processing of skin excisions

Microscopic evaluation

File:Pie chart of incidence and malignancy of pigmented skin lesions.png

Various diagnoses of pigmented skin lesions, by relative incidence upon biopsy, and malignancy potential.

Melanocytic lesions

Melanocytic lesions (including nevus) are the most common, and can be classified as follows:

	Atypia and/or dysplasia
	Low	High
Junction between epidermis and dermis	File:Histopathology of melanocytic nevus.jpg Junctional nevus	File:Histopathology of lentigo maligna.jpg Melanoma in situ
Dermis	File:Histopathology of dermal nevus, high magnification.jpg Dermal nevus	File:Histopathology of nodular melanoma, high magnification.jpg Invasive melanoma

Evaluation is largely based on the relative incidence and malignancy of various differential diagnoses (see pie chart). Main approaches are:

• Direct pattern recognition
• Systematic

Either way can be done by scrolling through the epidermis at intermediate magnification and then through the dermis at a lower magnification.

Non-melanocytic

• Seborrheic keratosis
  Seborrheic keratosis
• Basal cell carcinoma
  Basal cell carcinoma

Main page

• Main page of Patholines