Proliferating Pilar Tumors: Can Immunohistochemistry Differentiate Benign and Malignant Forms?

Am J Dermatopathol. 2021 Mar 1;43(3):198-201. doi: 10.1097/DAD.0000000000001743.

Abstract

Background: Proliferating pilar tumor (PPT) is an adnexal tumor of purported differentiation toward the follicular outer root sheath. Immunohistochemistry has been suggested to differentiate between benign and malignant forms.

Methods: Eleven benign (PPT) and 9 malignant PPT lesions were reviewed; Ki67, p27, and p53 were applied. The staining intensity (strong, moderate, weak, and negative), positive cell numbers, and marker indexes (%) were scored using image-analysis software (ViraSoft).

Results: Overall, there was no significant correlation between Ki67 and p53 and histopathological features. However, malignant PPTs had significantly lower numbers of p27-positive cells (P = 0.030).

Conclusions: Our study includes the largest group of patients in whom image analysis of p53, Ki67, and p27 has been used to try to separate benign from malignant lesions. Although there were no significant differences regarding Ki67 and p53, malignant lesions have a statistically lower expression of p27. Further studies may be needed to determine the clinical usefulness of image analysis in this differential diagnosis.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism*
  • Diagnosis, Differential
  • Female
  • Hair Follicle
  • Humans
  • Immunohistochemistry
  • Ki-67 Antigen / metabolism*
  • Male
  • Middle Aged
  • Neoplasm Invasiveness
  • Skin Neoplasms / diagnosis
  • Skin Neoplasms / metabolism*
  • Skin Neoplasms / pathology*
  • Tumor Burden
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • CDKN1B protein, human
  • Ki-67 Antigen
  • Tumor Suppressor Protein p53
  • Cyclin-Dependent Kinase Inhibitor p27