BAP1: case report and insight into a novel tumor suppressor

Our plain-English summary of BAP1: case report and insight into a novel tumor suppressor, by K. Ghosh, B. Modi, W.D. James, et al (BMC Dermatology, 2017).

The study

• Authors: K. Ghosh, B. Modi, W.D. James, B.C. Capell
• Journal: BMC Dermatology
• Published: 2017;17(1):13
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: BRCA1-Associated-Protein 1 (BAP1) is a dynamic tumor suppressor which, when mutated, has been associated with an increased risk of uveal melanoma, cutaneous melanoma, mesothelioma, and several other cancers. Germline BAP1 mutations have been extensively studied, where they have been found to cause hereditary cancer susceptibility. However, their sporadic counterparts, tumors that display a loss of BAP1 expression due to somatically arising mutations in the BAP1 gene, remain a poorly described entity.

Case Presentation: Here we present the case of a 49-year-old female who presented with an asymptomatic dome-shaped pink papule on the dorsal foot which was found on biopsy to be deficient in the BAP1 tumor suppressor. While the patient's family history did not suggest the presence of a familial cancer syndrome, germline genetic testing was performed and was negative. The patient underwent surgical excision of this sporadically appearing "BAPoma" by Mohs surgery.

Conclusions: Given the relatively banal clinical appearance of these dome-shaped neoplasms, sporadic BAPomas may often be overlooked by clinicians and dermatologists. In addition to providing a representative case, here we also provide a synopsis of the current understanding of these neoplasms, both in terms of the histopathological features, as well as the molecular mechanisms underlying BAP1 function and its ability to prevent tumorigenesis.

In plain English

This article was a case report of one patient, with a short discussion of earlier research on BAP1, a gene whose protein suppresses tumors. It did not study asbestos. Citing other studies, the background noted that inherited BAP1 mutations have been linked to higher risk of several cancers, including mesothelioma and melanoma. The patient, a 49-year-old woman, had a painless pink to purple dome-shaped bump on the third toe of the right foot. A biopsy showed atypical pigment cells (melanocytes) that had lost BAP1 staining, and the lesion was diagnosed as a "BAPoma". Because atypical cells reached the edges of the biopsy, the lesion was removed by Mohs surgery. Genetic testing for an inherited BAP1 mutation was negative. The authors said this result was evidence supporting a sporadic, non-inherited BAP1 mutation in the lesion. Citing a lack of clear guidelines on screening for other cancers such as mesothelioma, the authors recommended only continued skin screening. The authors concluded that these tumors may often be overlooked because they look unremarkable.

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 of a single patient, followed by a brief discussion of published research on BAP1 function and on the tissue features of BAP1-deficient skin tumors
• Who was studied: One 49-year-old female patient seen during routine care in a dermatology clinic (the authors are at the University of Pennsylvania). She had a history of actinic keratoses. Her family history included colon cancer and prostate cancer. No date of care is given.
• Exposure: No asbestos or other environmental exposure was studied or reported. The article concerns loss of the BAP1 tumor-suppressor protein in a skin lesion.
• Main results:
  • The lesion on the patient's right third toe stained positive for MART-1, a melanocyte marker.
  • BAP1 staining of the lesion was negative, leading to a diagnosis of a BAPoma with epithelioid atypia and rare mitoses.
  • Atypical cells extended to the biopsy margins, so the patient underwent Mohs surgery to clear the lesion.
  • Sequencing and deletion and duplication analysis of the patient's BAP1 gene for a germline (inherited) mutation was negative. The authors said this was evidence supporting a sporadic BAP1 mutation in the lesion.
  • There are no clear guidelines on screening such patients for other cancers such as renal cell carcinoma or mesothelioma, so only continued skin screening was recommended.
• The authors' conclusion: The authors concluded that, because these dome-shaped growths look relatively ordinary, sporadic BAPomas may often be overlooked by clinicians and dermatologists.

Topics

Medical terms in this study, explained in our Lexicon: BAP1, Mesothelioma, BAP1 Tumor Predisposition Syndrome, Biopsy, Neoplasm, Carcinogenesis.

Related studies

• Case report: Onychopapilloma in a patient with BAP1 tumor predisposition syndrome-a useful clinical marker? — E. Sjøstrøm, L.B. Ahlborn, et al. (2026)
• Comprehensive review of BAP1 tumor predisposition syndrome with report of two new cases — K. Rai, R. Pilarski, et al. (2016)
• Tumours associated with BAP1 mutations — R. Murali, T. Wiesner, et al. (2013)
• Different prognostic roles of tumor suppressor gene BAP1 in cancer: A systematic review with meta-analysis — C. Luchini, N. Veronese, et al. (2016)
• Functional differences between wild-type and mutant-type BRCA1-associated protein 1 tumor suppressor against malignant mesothelioma cells — S. Hakiri, H. Osada, et al. (2015)
• Histologically Diverse BAP1-Deficient Melanocytic Tumors in a Patient With BAP1 Tumor Predisposition Syndrome — A. Louw, J. Creaney, et al. (2020)

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