Skin biopsies are taken for the following reasons.
#! To make or confirm a clinical diagnosis
#! To remove a skin lesion
#! To determine whether margins of excision are adequate
Explanation: Skin biopsies are taken to remove a lesion, to determine whether margins of excision are adequate, and to make or confirm a clinical diagnosis. They may also be necessary for research.
Which of the following skin specimens is not used for dermatopathology?
# Excision biopsy
#! Skin scrapings
# Punch biopsies
Explanation: Skin specimens include excision, incision, shave, punch biopsies and curettings. Skin scrapings are performed for potassium hydroxide microscopy and fungal culture.
Regarding biopsy specimens:
# The majority of punch biopsies use 10mm elliptical blades || Punch biopsies are most frequently 3 to 5 mm in diameter with round blade.
# The specimen should be removed from fixative after 2 hours || Specimens should normally remain in fixative for at least 24 hours.
# Paraffin blocks are sliced into 3-5 mm sections || Paraffin blocks are sliced into 3-5 micron sections.
#! Skin specimens are usually stained using haematoxylin and eosin || Standard staining is with haematoxylin and eosin (H and E). Additional stains may be necessary when the diagnosis is unclear and to determine the nature of specific cells and structures.
# Haematoxylin is acidic and stains nuclei red || Haematoxylin is alkaline and stains nuclei blue.
#! Eosin is acidic and stains cell cytoplasm red
# Direct immunofluorescence is used to identify tumours || Direct immunofluorescence stains immunoglobulins and is especially useful to identify immunobullous diseases.
# Immunohistochemistry is used to identify tumours ||Immunohistochemistry is used to label immunoreactive materials to determine cell origin of tumours and identify certain infections.