2025 Clinician Corner - Histologic changes of basal cell carcinomas during vismodegib treatment

Abstract 

We report a case of a 63-year-old man with a history of numerous basal cell carcinomas (BCCs) on vismodegib who developed a pink subcutaneous nodule that was thought to be either a BCC or an epidermal inclusion cyst. Sections displayed a dome-shaped lesion composed of large dermal nodules of epithelioid cells with variable cytology. Some of the dermal nodules demonstrated squamatization of the epithelioid cells while others had a predominantly basaloid phenotype. Central necrosis was present in the majority of the large dermal nodules, but the lesion did not stain with CK7 or CK20, helping to rule out internal metastases. The epithelial nodules stained strongly with pancytokeratin (AE1/AE3), p40, and stained lightly with BCL-2, supporting the diagnosis of BCC. However, Ber-EP4 being negative and the presence of significant squamatization suggest vismodegib can alter both the histological and immunophenotype of BCCs. This phenomenon has rarely been reported in literature.  

Keywords:  Basal cell carcinoma; histology; squamous differentiation; vismodegib 

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Faculty credentials/disclosure 

The planners and faculty for this activity have no relevant financial relationships to disclose. The patient consented to the publication of this report.

Process

Click the "add to cart/begin" button, pay any relevant fee, take the quiz, complete the evaluation, and claim your CME credit.  You must achieve 100% on the quiz with unlimited attempts available.

  • By completing this process, you are attesting that you have read the journal article.

Expiration date:

Credit eligibility for this article is set to expire on March 1, 2026.

Learning Objectives

After completing the article, the learner should be able to:

  • Describe the mechanism of action of vismodegib and its role in the treatment of locally advanced basal cell carcinoma (BCC). 
  • Recognize the histological markers commonly associated with BCC and understand how vismodegib treatment can alter these markers. 
  • Differentiate between BCC and basosquamous carcinoma based on histological features and immunohistochemical staining patterns, especially in patients undergoing vismodegib therapy. 

Key points 

  • The histology and immunophenotype of basal cell carcinomas can be altered by vismodegib.  

  • Squamous differentiation and the keratinizing phenomena can be observed in basal cell carcinomas being treated with vismodegib. 

  • Due to these alterations, patients on vismodegib should maintain regular skin checks and have any suspicious lesions biopsied.

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Course summary
Available credit: 
  • 1.00 American Board of Internal Medicine (ABIM) MOC Part 2
    Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.00 MOC points in the American Board of Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.
  • 1.00 American Board of Surgery (ABS) Accredited CME
    Successful completion of this CME activity enables the learner to earn credit toward the CME requirement of the American Board of Surgery’s Continuous Certification program. It is the CME activity provider's responsibility to submit learner completion information to ACCME for the purpose of granting ABS credit.
  • 1.00 AMA PRA Category 1 Credit™
    The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
  • 1.00 Attendance
Course opens: 
03/01/2025
Course expires: 
03/01/2026
Cost:
$25.00
Rating: 
0

  • Nicole Remmert, BS1, Lauren Dixon, MSBS1, Jay Truitt, MD, PhD, PharmD, MPH2, Sina Aboutalebi, MD3, and Michelle Tarbox, MD2 

    1 School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA 

    2 Department of Dermatology, Texas Tech University Health Sciences Center, Lubbock, Texas, USA 

    3 Abilene Dermatology and Skin Surgery Center, Abilene, Texas, USA 

Accreditation

The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Designation

AMA PRA Category 1 Credit™

The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

ABS CC

Successful completion of this CME activity enables the learner to earn credit toward the CME requirement of the American Board of Surgery’s Continuous Certification program. It is the CME activity provider's responsibility to submit learner completion information to ACCME for the purpose of granting ABS credit.

ABIM MOC

 Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.0 MOC points in the American Board of Internal Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.

 

Available Credit

  • 1.00 American Board of Internal Medicine (ABIM) MOC Part 2
    Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.00 MOC points in the American Board of Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.
  • 1.00 American Board of Surgery (ABS) Accredited CME
    Successful completion of this CME activity enables the learner to earn credit toward the CME requirement of the American Board of Surgery’s Continuous Certification program. It is the CME activity provider's responsibility to submit learner completion information to ACCME for the purpose of granting ABS credit.
  • 1.00 AMA PRA Category 1 Credit™
    The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
  • 1.00 Attendance

Price

Cost:
$25.00
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