Mohs Micrographic Surgery and Cutaneous Oncology Flashcards
Mohs provides the highest cure rate for tumours that spread by direct extension.
T
MOHs has clearance approx 80% for recurrence rate
F >90%
Critical in the process is that the skin edge and deep surface are visualized in one plane on the glass slide, and thus the entire margin can be analysed
T
Mohs surgery originally involved the use of zinc chloride (as a fixative), combined with stibnite (as permeant) and bloodroot powder (Sanguinaria Canadensis) (as agglutinant).
T This is the same as black salve!
Conventional breadloaf sectioning of tumours allows for examination of 10% of the tumour’s margin.
F
Indications for MOHs micrographic surgery includes tumour larger than 2cm in diameter
T
Tumours of the skin of the upper lips are usually SCC, while those of the cutaneous lower lip are most commonly BCC.
F Other way round.
Most Mohs laboratories use routine hematoxylin and eosin staining for all specimens.
T
Technical errors are the most common cause of local recurrences after Mohs surgery.
T
Large or thick tumours may be debulked using a curette as this may further delineate margins and reduce the number of layers necessary to obtain clear margins
T
A saucer-shaped specimen with 45degree bevelled edges is ideal so that the specimen may be flattened
F 30 degrees. Flattening means that the bottom and margins can be sectioned by the Mohs technician in the same plane
The specimen has its non-epidermal edges stained to allow proper orientation. At least four colours are used for each specimen to allow for adequate orientation
F Two to three colours
In the laboratory, vertical sections are taken
F Specimen is placed bottom side up toward the microtome stage to allow horizontal sections
The tissue may be immediately frozen with tetrafluoroethylchloride or liquid nitrogen and then transferred to the cryostat for thorough freezing
T
Toluidine blue can be used for BCCs but has poor optical clarity
F Favoured by some for its optical clarity, but the process of immunostatins is impractical for routine use
Infiltrative BCC is not distinctive clinically, but histologically contains islands of tumour cells with a spiked appearance in narrow cords within a hyalinised stroma
T
BCCs with aggressive histology (ie. ulcerative, metatypical, morpheaform, infiltrative forms) require more Mohs layers to achieve tumour-free margins.
T
BCC tumour size does not affect the extent of subclinical spread.
F
Recurrent BCCs after radiotherapy often have morphoeaform or metatypical patterns.
T
Metastatic BCC occurs in less than 0.5% of cases.
T
Risk factors for metastatic BCC include tumour invasion into cartilage, bone, skeletal muscle or parotid gland, previous XRT and previous treatment with any modality.
T
The nose is the most common site from which metastatic spread of BCC occurs.
F The ear.
BCC metastasis occurs haematogenously only to lungs, bone&skin.
F Also through lymphatics.
