Testis & paratestis

Epididymal tumors

Adenocarcinoma of epididymis

Last author update: 1 October 2014
Last staff update: 28 March 2022

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PubMed Search: Adenocarcinoma [title] testis

Swapnil U. Rane, M.D.
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Cite this page: Rane S. Adenocarcinoma of epididymis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisepidadenocarcinoma.html. Accessed May 19th, 2024.
Definition / general
  • Adenocarcinoma arising de novo in epididymis
  • Also called papillary adenocarcinoma, cystadenocarcinoma, papillary cystadenocarcinoma
  • Extremely rare
  • Age range: 27 - 82 years, mean age: 67 years
  • Tumors are centered on epididymis; may be confined to epididymis or may infiltrate adjacent tissue
  • Believed to arise from metaplastic epididymal epithelium
Clinical features
  • Usually presents as palpable scrotal mass with / without pain and hydrocele
  • Confirmation and differentiation from other malignancies in this region is possible only on histology
  • No specific laboratory features
  • Negative serum markers for sex cord and germ cell tumors
Prognostic factors
  • Due to rarity of tumor, prognostic features are unknown
  • A large proportion of tumors reported in literature metastasize at presentation or later
Case reports
  • High inguinal orchidectomy with retroperitoneal lymph node dissection
  • Adjuvant chemotherapy or radiation therapy
Gross description
  • 1 - 7 cm
  • Infiltrative tumor either confined to epididymis or infiltrating adjacent soft tissue
  • Tan to grey white cut surface with frequent foci of hemorrhage and necrosis
Microscopic (histologic) description
  • Tubular, tubulopapillary, papillary and cystic growth patterns, which often occur in combinations and varying degrees of complexity
  • Also an undifferentiated sheet like pattern
  • Tumor cells are cuboidal to columnar, predominantly clear, rich in glycogen
  • Often infiltrates into epididymal smooth muscle or adjacent soft tissue
  • Necrosis is usually present
  • Psammoma bodies are rare
Microscopic (histologic) images

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Adenocarcinoma of rete testis

Positive stains
Negative stains
Differential diagnosis
  • Other primary tumors of epididymis and paratesticular region
    • Adenomatoid tumor
      • Usually lack clear cells
      • Tubules lined by low cuboidal to flat cells which may be vacuolated but are not watery clear as seen in primary epididymal adenocarcinoma
      • Low grade nuclear features
      • Mesothelial origin
      • IHC for mesothelial markers usually positive
    • Carcinoma of rete testis
      • Centered on testicular hilum, associated with transition to normal rete testis
      • Elongated tubular pattern, unlike the round tubular pattern of epididymal adenocarcinomas
    • Mesothelioma
      • No clear cells
      • Calretinin, HBME1, WT1, mesothelin positive
    • Serous cystadenoma of epididymis
      • Lack of invasive features
      • Low grade cellular features
      • Associated with von Hippel-Lindau syndrome
    • Serous papillary carcinoma: infiltrates as single isolated papillae, no tubules
  • Metastatic prostatic carcinoma: PSA+
  • Metastatic GI adenocarcinoma: CEA+, CK20+; variable mucin
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