4 August 2005 – Case of the Week #15


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We thank Dr. Peter Morawiecki, Great Lakes, Illinois (USA) for contributing this case.  We invite you to contribute a Case of the Week by emailing NPernick@PathologyOutlines.com with microscopic images (any size, we will shrink if necessary) in JPG or GIF format, a short clinical history and any other images (gross, immunostains, EM, etc.) that you have and that may be helpful or interesting.  We will write the discussion (unless you want to contribute to it).  We will list you as the contributor, and send you a check for $35 (US) for your time if we use the case.  Please only send cases with a definitive diagnosis. 


Case of the Week #15


A 62 year old black man had a more than 1 year history of a slowly enlarging thumb mass.  Clinically, it was believed to be an epidermal cyst.  Xrays failed to show any abnormalities.


Microscopic images:  low power - image1, image2, image3;

medium power - image4, image5, image6, image7

high power - image8, image9, image10, image 11


What is your diagnosis? 


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Diagnosis:  Aggressive digital papillary adenocarcinoma




Aggressive digital papillary adenocarcinoma is a rare sweat gland tumor that occurs primarily on the digits of the hands and feet and adjacent skin.  Although these tumors were initially divided into adenomas and adenocarcinomas, a recent AFIP study concluded that histologic features could not predict which tumors would act aggressively, and the authors recommended that all of these tumors be called adenocarcinomas (Am J Surg Pathol 2000;24:775).


These tumors primarily affect males, with a mean age of 52 years (range 19-83 years).  Average tumor size is 2 cm (range 0.4 to 4 cm), and tumors are present for an average of 2-3 years before excision.  They are usually (85%) on the hand, with the remainder on the feet.  They frequently are associated with pain. 


Morphologically, they have a distinctive solid and cystic growth pattern with either true papillae containing fibrovascular cores or pseudopapillae composed of heaped up epithelium.  Although not prominent in this case, there are usually fused back to back gland-like structures in solid areas.  Cystic areas are formed by central degeneration or necrosis of solid areas, or from collection of eosinophilic secretory material.  In 18% of cases, only solid areas are present without cystic spaces.  There is variable tumor circumscription, mitotic activity, atypia and necrosis.  There may be focal clear cell change, squamous differentiation or apocrine-type secretion.


These tumors may recur, particularly if the initial excision is inadequate, and no reexcision or amputation is performed.  They are considered to have a low but significant (14%) metastatic potential.  Recommended treatment is reexcision or amputation as necessary to ensure adequate margins.


The differential diagnosis includes other eccrine tumors, including malignant eccrine acrospiroma / hidradenoma, malignant eccrine spiradenoma and papillary eccrine adenoma.  Malignant eccrine acrospiroma typically does not occur in the digits, or have papillary patterns or back to back glands.  Malignant eccrine spiradenoma typically has a two cell pattern of central basaloid cells and large peripheral cells, and occurs anywhere on the body, not limited to the digits.  They also lack papillary patterns and back to back glands.  Papillary eccrine adenoma is a well circumscribed tumor with dilated ducts of variable size, and a double layer of epithelial cells forming papillae that project into the lumen.  It does occur in the digits, but almost always has benign behavior.


This particular case was sent to the AFIP, whose diagnosis was “consistent with aggressive digital papillary adenocarcinoma.”  However, other dermatopathologists called it a cystic hidradenoma or an acrospiroma.




Nat Pernick, M.D.
PathologyOutlines.com, LLC
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