Penile intraepithelial neoplasia

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Penile intraepithelial neoplasia, abbreviated PeIN, is the precursor of squamous cell carcinoma of the penis.

Penile intraepithelial neoplasia
Diagnosis in short

Penile intraepithelial neoplasia (undifferentiated subtype). H&E stain.
Subtypes differentiated PeIN, undifferentiated PeIN
LM DDx squamous cell carcinoma of the penis, squamous hyperplasia
IHC p16 +ve (uPeIN) -ve (dPeIN), p53 -ve (uPeIN) +ve (dPeIN)
Site penectomy grossing

Associated Dx HPV infection (undifferentiated PeIN), lichen sclerosus or BXO (differentiated PeIN)
Prevalence uncommon
Prognosis good
Clin. DDx squamous cell carcinoma of the penis, lichen sclerosis, phimosis

It may be abbreviated PIN;[1] however, this can cause confusion with the prostatic intraepithelial neoplasia (the presursor of prostate carcinoma).

General

Microscopic

Subclassified as:[2]

  • Undifferentiated PeIN (uPeIN).
  • Differentiated PeIN (dPeIN).

Note:

Undifferentiated penile intraepithelial neoplasia

Features:

  • Increased NC ratio.
  • Multinucleation.
  • Lack of maturation to surface - not that useful.
    • May have "vertical streaming" - the long axis of the cells are perpendicular to the free surface & basement membrane.
  • Apical mitoses.

DDx:

Differentiated penile intraepithelial neoplasia

Features:

  • Thickening of the stratum spinosum (acanthosis).
  • Elongation of rete ridges with bridging/anastomoses between rete ridges.
  • Nuclear atypia - esp. of the basal layer.
  • Nuclei in stratum corneum (parakeratosis).
  • +/-Atypical mitoses.

DDx:

Images

IHC

  • p16 -ve in dPeIN,[3] +ve in uPeIN.

See also

References

  1. Porter, WM.; Francis, N.; Hawkins, D.; Dinneen, M.; Bunker, CB. (Dec 2002). "Penile intraepithelial neoplasia: clinical spectrum and treatment of 35 cases.". Br J Dermatol 147 (6): 1159-65. PMID 12452865.
  2. Velazquez, EF.; Chaux, A.; Cubilla, AL. (May 2012). "Histologic classification of penile intraepithelial neoplasia.". Semin Diagn Pathol 29 (2): 96-102. PMID 22641959.
  3. Oertell, J.; Caballero, C.; Iglesias, M.; Chaux, A.; Amat, L.; Ayala, E.; Rodríguez, I.; Velázquez, EF. et al. (May 2011). "Differentiated precursor lesions and low-grade variants of squamous cell carcinomas are frequent findings in foreskins of patients from a region of high penile cancer incidence.". Histopathology 58 (6): 925-33. doi:10.1111/j.1365-2559.2011.03816.x. PMID 21585428.