Metastatic Melanoma With Papillary Features: A Mimic and Possible Diagnostic Pitfall

Our plain-English summary of Metastatic Melanoma With Papillary Features: A Mimic and Possible Diagnostic Pitfall, by A. Valero-Torres, V.G. Prieto, P. Nagarajan, et al (The American Journal of Dermatopathology, 2017).

The study

• Authors: A. Valero-Torres, V.G. Prieto, P. Nagarajan, C.A. Torres-Cabala, M.T. Tetzlaff, J.L. Curry, D. Ivan, P.P. Aung
• Journal: The American Journal of Dermatopathology
• Published: 2017;39(6):468-470
• Type of article: Case report
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Papillary and pseudopapillary features are histopathologic findings typically associated with carcinomas (thyroid, pancreas, breast, prostate, bladder, kidney, or ovary) or mesothelioma. Melanoma is typically composed of nested and variably pigmented atypical cells. Here, we report a case of in-transit metastasis of melanoma presenting with prominent papillary features, and we discuss the differential diagnoses of neoplasms with papillary features. This case report suggests that the spectrum of neoplasms with papillary features should be expanded to include melanoma, a pattern that, to the best of our knowledge, is uncommon.

In plain English

This article was a case report about one patient at The University of Texas MD Anderson Cancer Center in Houston. A 76-year-old white man with a history of nonmelanoma skin cancer had multiple ill-defined, scaly pink bumps and nodules on his scalp. A biopsy from the left scalp showed a cancer mainly in the dermis (a deeper layer of the skin). It had prominent papillary (finger-like) features and no melanin pigment. Because this pattern is typical of other cancers, the doctors first considered spread from cancers of the thyroid, pancreas, breast, prostate or kidney, and also melanoma. They considered mesothelioma but left it off their first list. They judged it extremely unlikely to spread to the scalp without a known primary mesothelioma. Tumor cells reacted only with melanoma markers, and the final diagnosis was metastatic melanoma. A second biopsy found the primary melanoma, which had no papillary features. After surgery, no regional lymph node involvement was found. The patient was alive and disease free at 14 months of follow-up. The authors concluded that melanoma with prominent papillary features is an uncommon variant that could be easily misdiagnosed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient)
• Who was studied: One 76-year-old white man with a history of nonmelanoma skin cancer, seen at MD Anderson (Houston, Texas) with multiple scalp papules and nodules
• Main results:
  • The biopsy from the left scalp showed a malignant epithelioid tumor mainly in the dermis, with prominent papillary features and no melanin pigment inside the cells
  • The initial list of possible diagnoses included spread from carcinoma of the thyroid, pancreas, breast, prostate, or kidney, as well as melanoma
  • Mesothelioma was considered on the basis of appearance but was left out of the first list of possible diagnoses, because spread to the scalp without a known primary mesothelioma was considered extremely unlikely
  • On immunohistochemical staining, tumor cells reacted only with the pan-melanoma marker cocktail. The final diagnosis was metastatic melanoma involving the dermis
  • A second biopsy, from a separate nodule on the vertex (top) of the scalp, showed primary invasive melanoma without papillary features. It had a Breslow thickness of at least 0.75 mm and 2 mitotic figures in the dermal component
  • The wide local excision showed invasive nodular melanoma with a Breslow thickness of 2.4 mm, without papillary features, and with no regional lymph node involvement
  • The patient was alive and disease free 14 months after surgical treatment
• The authors' conclusion: The authors concluded that melanoma with prominent papillary features is an uncommon variant that could be easily misdiagnosed, especially when the lesion is mainly in the dermis and the patient has no known history of melanoma. They stated that patient history, looking for melanin pigment and immunohistochemical studies will help establish the correct diagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Carcinoma, Mesothelioma, Metastasis, Neoplasm.

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