[526] Aggressive Digital Papillary Adenocarcinoma: Clinicopathologic Study of 29 Cases of a Rare Neoplasm with New Observations.

Ravi Suchak, Wei-Lien Wang, Victor G Prieto, Alexander J Lazar, Eduardo Calonje. St John's Institute of Dermatology, London, United Kingdom; The University of Texas MD Anderson Cancer Center, Houston

Background: Aggressive digital papillary adenocarcinoma (ADPA) was originally divided into benign and malignant categories based on histologic features. A later study defined a morphologic spectrum with a high recurrence and significant metastatic potential. All are now regarded as adenocarcinoma and with histologic features offering no distinction. There are only 2 large published studies.
Design: All cases with available slides diagnosed as ADPA were retrieved from our files (n=29). The slides were reviewed by two of the authors, and tumor morphology correlated with clinical features and outcome.
Results: Males were predominantly affected (n=28). Full clinical details were available for 27 patients. All involved a finger (n=23) or toe (n=4). Histopathologically, the tumor involved the dermis +/- subcutis. Epidermal hyperplasia (n=3), ulceration (n=2) and focal epidermal connection (n=1) were noted on occasion. The tumors had a lobular architecture (n=26) with a focally infiltrative pattern. They were unencapsulated with fibrous to sclerotic bands surrounding tumor lobules (n=17). Lesions were predominantly solid (n=23), with a cystic component ranging from <10% to 30% of observed tumor area. 6 had a cystic component comprising 50% or more of the tumour. Papillary projections were: prominent (n=9), focal (n=14), or not identified (n=6). Within the solid component, tubular structures were present at least focally in all cases. Focal keratinization was rare (n=2). Cytologic atypia ranged from mild to moderate (n=27), but was focally severe in 2 cases. Mitotic count ranged from <1 to 18 per square mm with focal necrosis in 6 cases. Stromal hyalinization was present at least focally in most cases, and was prominent centrally in some. 3 cases had prominent vascular dilatation with thrombi. Inflammation was not prominent and neurovascular invasion was not identified. All cases were treated by complete exicison; follow-up (n=18; range, 2m-10y) revealed local recurrence (n=3) and metastatic disease (n=3; lymph node in 1 and lungs in 2).
Conclusions: Recurrence rates in ADPA may not be as high as previously reported, although given the metastatic potential, they are best regarded as malignant and completely excised. ADPA can have a significant tubular/solid pattern with only a focal papillary component, and this may represent a pitfall in limited biopsies.
Category: Dermatopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 116, Wednesday Afternoon


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