To the editor:
We read a recent case report entitled “Aggressive Digital Papillary Adenocarcinoma with Multiple Organ Metastases: A Case Report and Review of the Literature” published in the 2016 December issue of the American Journal of Dermatopathology.1 The authors described a 73-year-old woman who developed a gradually growing 3-mm nodule on her left second toe. An excisional biopsy was performed, and the lesion was initially considered by the authors as spiradenoma after histological examination. Re-excision was not performed, and subsequently, the patient had local recurrence 2 years later and multiple pulmonary metastasis 31 months later. On histological examination, all tumors (the primary tumor, locally recurrent tumor, and lung metastases) showed the same microscopic features and consisted of both epithelial and myoepithelial components confirmed by immunohistochemistry. On the basis of these findings, the authors finally diagnosed the tumor as aggressive digital papillary adenocarcinoma with multiple pulmonary metastases, and subsequently, the patient died of wide-spread metastatic disease. The documentation of the case from the initial presentation, recurrence, and eventual pulmonary metastases with photographs of the clinical, radiographic, and microscopic studies is commendable. However, there are 2 issues that we would like to comment on.
The first issue pertains to the true nature and morphologic features of the tumor described by the authors in this case report. As seen in microscopic photomicrographs and corroborated by immunohistochemistry, the primary, recurrent, and metastatic tumors were all made up of a dual cell population, with the luminal cells staining for epithelial markers and the remaining tumor cells for myoepithelial markers. In our view, this tumor is clearly an epithelial–myoepithelial carcinoma rather than an adenocarcinoma; the latter should be composed of neoplastic glandular epithelial cells only. Epithelial–myoepithelial carcinoma is rare, but it has been well documented in the salivary gland2 and in the breast under a different term, namely, malignant adenomyoepithelioma.3 Although epithelial–myoepithelial carcinoma has not been described in the skin to the best of our knowledge, we believe it surely exists in the skin and must have been misdiagnosed as others. This case documented in detail by Kobayashi et al1 indeed represents such an example, in our opinion.
The second issue pertains to the omission of the references cited by the authors of an article entitled “Is aggressive digital papillary adenocarcinoma really aggressive digital papillary adenocarcinoma?” This was an article published in July of 2014 as an editorial in the journal of Dermatology Practical and Conceptual,4 where a relook into the nomenclature of the so-called aggressive digital papillary adenocarcinoma had been made. In that editorial, Chen and Asgari asked 4 questions, namely:
- Is aggressive digital papillary adenocarcinoma really aggressive?
- Does it only occur at digital location?
- Does it always have microscopic papillary features?
- Is it really adenocarcinoma?
They addressed each of these questions critically with thorough historical literature review and concluded with these words: “In summary, the so-called aggressive digital papillary adenocarcinoma is not an aggressive tumor. There is no reason to believe that it is restricted to digital location. It does not always have microscopic papillary feature and furthermore it might be adenomyoepithelial tumor rather than adenocarcinoma. Thus, the so-called aggressive digital papillary adenocarcinoma, in our opinion, is not really aggressive digital papillary adenocarcinoma.”4 Although the case presented by Kobayashi et al1 had an aggressive clinical course, most of the so-called aggressive digital papillary adenocarcinoma behave like a low-grade malignant neoplasm.4 The case report by Kobayashi et al further supports the notion that the so-called aggressive digital papillary adenocarcinoma is not really adenocarcinoma but adenomyoepithelial tumor (such as epithelial–myoepithelial carcinoma) as proposed by Chen and Asgari.4
1. Kobayashi T, Hiura A, Oishi K, et al. Aggressive digital papillary adenocarcinoma with multiple organ metastases: a case report and review of the literature. Am J Dermatopathol. 2016;38:910–914.
2. Seethala RR, Barnes EL, Hunt JL. Epithelial-myoepithelial carcinoma: a review of the clinicopathologic spectrum and immunophenotypic characteristics in 61 tumors of the salivary glands and upper aerodigestive tract. Am J Surg Pathol. 2007;31:44–57. Erratum in: Am J Surg Pathol. 2008;32:1923.
3. Ahmed AA, Heller DS. Malignant adenomyoepithelioma of the breast with malignant proliferation of epithelial and myoepithelial elements: a case report and review of the literature. Arch Pathol Lab Med. 2000;124:632–636.
4. Chen S, Asgari M. Is aggressive digital papillary adenocarcinoma really aggressive digital papillary adenocarcinoma? Dermatol Pract Concept 2014;4:33–35.