Prostatic intraepithelial neoplasia (PIN)
High grade PIN - Foamy gland pattern

Author: Nicholas Reder, M.D. (see Authors page)
Editor: Maria Tretiakova, M.D.

Revised: 4 December 2015, last major update December 2015

Copyright: (c) 2003-2015,, Inc.

PubMed Search: High grade prostatic intraepithelial neoplasia [title] foamy
Cite this page: High grade PIN - Foamy gland pattern. website. Accessed April 23rd, 2018.
Definition / general
  • An unusual form of high grade PIN that is characterized by a distinctive foamy cytoplasm and small, bland, basally located nuclei
Essential features
  • Abundant xanthomatous (foamy) cytoplasm
  • Minimal nuclear enlargement and rare or absent prominent nucleoli
  • Due to its rarity, the clinical behavior of foamy gland PIN is not known; however, foamy gland carcinoma has worse prognosis than classic acinar adenocarcinoma in spite of its innocuous appearance (Am J Surg Pathol 1996;20:419, Ann Diagn Pathol 2014;18:271)
Case reports
Microscopic (histologic) description
  • Pale / foamy cells with voluminous xanthomatous cytoplasm, forming papillary infoldings, tufting and cribriform patterns
  • Nuclei are small, bland, mildly hyperchromatic and basally located
  • Transitions between foamy PIN and ordinary high grade PIN with prominent nucleoli may be seen within a single gland
Microscopic (histologic) images
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Foamy PIN, images c/o Nicholas Reder, M.D.

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Abundant foamy cytoplasm

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Small dark nuclei

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Positive stains
Differential diagnosis
  • Clear cell cribriform hyperplasia: crowded glands with pale clear cytoplasm, round uniform nuclei and prominent basal layer; typically present in the transition zone
  • Foamy gland carcinoma: similar cytology, but absent basal cell layer, smaller glands and infiltrative pattern
  • Low grade transition zone carcinoma:
    • Uniform tall columnar cells with a modest amount of pale to clear cytoplasm
    • The nuclei are hyperchromatic, basally located, and have prominent nucleoli
    • Grows in expansile nodules in the transition zone
Additional references