Variants of Melanoma that can be mistaken for a Benign Lesion :
"Wolf in Sheep's Clothing"
"Mistaking an aggressive malignant tumour for a benign harmless lesion can lead to disastrous consequence"
Histolopathological examination of melanocytic lesions constitutes a large proportion of a pathologist's daily workload.
These lesions are excised either for cosmetic reason or when they are clinically atypical and excised to rule out melanoma.
Dermatologists, surgeons, and oncologists depend on the pathologist for a prompt, accurate and complete diagnoses in a case of melanoma.
The histological diagnosis of benign melanocytic nevi and malignant melanocytic lesions can be readily made in straightforward cases, by applying the well-recognized pathological criteria.
A large number of melanocytic lesions fall into a borderline area that can be a problem to the most experienced of pathologists.
Some pigmented skin lesions can be difficult to classify due to unusual features.
One should avoid making both under and over diagnosis of melanoma by systematically approaching these lesions.
Diagnostic error can delay appropriate clinical management of the patient and may lead to legal problems.
The following variants of melanoma may mimic benign lesions and should be carefully examined to establish the diagnosis.
Detailed clinical history is essential before looking at a pigmented lesion. The following information should be provided to the pathologist:
1) Age of the patient
2) Site of the lesion
3) Whether there was any previous history of shave biopsy or incomplete excision.
The entire tissue with lesion should be examined, with levels cut where appropriate.
|General features in
favour of Melanoma:
2) Peripheral epidermal invasion
3) Heavy pigmentation
4) Deep and abnormal mitosis
5) Nuclear pleomorphism
6) HMB45 positive deep dermal cells
7) Vascular invasion, neurotropism, satellites
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