[546] Clinico-Pathological Correlates of Vulvar Melanosis with Melanocytic Atypia

Igor Shendrik, Arthur N Crowson. Regional Medical Laboratory, Tulsa, OK; University of Oklahoma, Oklahoma City, OK

Background: Vulvar melanoma (VMM) is a rare malignancy of hair bearing and glabrous skin, which commonly denotes a poor prognosis. Early VMM in situ may not have a clearly defined precursor and is a well recognized clinical and histologic mimic of vulvar melanosis. Cases of vulvar melanosis with melanocytic atypia present a considerable diagnostic challenge.
Design: A 10 year retrospective search of our laboratory database was performed for cases of vulvar melanosis and VMM. All patients (pts) demonstrating melanocytic atypia and/or melanoma were subsequently longitudinally reviewed.
Results: Vulvar melanosis (Vm) was identified in 139 biopsies of 100 pts. Of those 14 pts originally demonstrated different degrees of cytologic atypia: mild (8), moderate (5) and severe (1). Two pts with high grade dysplasia (17 and 28 years old) were reclassified as atypical genital nevus on re-excision. Complete excision of the pigmented lesions without recurrences was achieved in the majority of the pts with high grade atypia (5 of 6) and in half of the pts with mild atypia. One pt had multiple excisions of lesions with moderate atypia during the course of 6 years without progression to melanoma. There were 13 pts with VMM (5 mucosal lentiginous, 4 superficial spreading, 2 nodular and 2 NOS types) ranging from 40 to 92 years of age (mean = 70 years). All VMM pts presented with either melanoma or at least severe melanocytic atypia on the initial biopsy, shortly followed by a diagnosis of VMM. Vm with atypia was subsequently identified in 3 melanoma pts, demonstrating morphological features of de-novo intraepidermal epithelioid melanocytic atypia.
Conclusions: 1. Vm with mild atypia is not usually associated with either progression to the melanoma or lesional recurrence.
2. Rare cases of Vm with moderate atypia may present with multiple recurrences without progression to VMM, suggestive of field effect.
3. VMM appears to arise de-novo with no identifiable precursor lesion in the majority of cases.
Category: Dermatopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 115, Wednesday Afternoon

 

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