Adenomatoid Tumor

Adenomatoid Tumor

Steven S. Shen, MD, PhD

Jae Y. Ro, MD, PhD

Adenomatoid tumor, the most common adnexal tumor, presents as a well-demarcated white-tan firm mass image in the epididymis. It lacks hemorrhage, necrosis, or gross infiltrative characteristics.

Adenomatoid tumor is composed of gland-like spaces lined by flattened cells. A few isolated cells with cytoplasmic vacuoles mimic signet ring cells image. A variety of patterns are usually present.



  • Benign paratesticular tumor of mesothelial cell origin, which has a variety of growth patterns, including glands, cysts, tubules, cords, or isolated cells



  • Incidence

    • Most common tumor of testicular adnexa

  • Age

    • Range: 18-79 years (average: 36 years)


  • Usually asymptomatic, small and solid intrascrotal mass

  • Most commonly occurs in head of epididymis, although it may occur in tunica vaginalis, albuginea, and rete testis

  • Tumors may rarely be intratesticular and involve parietal tunica or spermatic cord


  • Surgical approaches

    • Surgical excision is curative


  • Benign clinical course


General Features

  • Small, well-circumscribed, white-tan, homogeneous, firm mass

  • No hemorrhage or necrosis


  • < 5 cm (majority < 2 cm)


Histologic Features

  • Well-circumscribed, unencapsulated mass

  • Tubules; gland-like, irregular cystic spaces or channels

  • Nests and cords; true solid pattern rare

  • Cuboidal, flat, or ovoid cells with round nuclei and abundant dense cytoplasm with vacuoles

  • May show signet ring cell appearance

  • May be cellular or infarcted

  • Intervening fibrous stroma ± smooth muscle fibers

  • Lymphoid aggregates may be prominent within or at periphery of tumor

  • Rare tumors may be infarcted

    • Surrounding inflammation and reactive myofibroblastic proliferation may simulate invasion

Cytologic Features

  • Eosinophilic, vacuolated, signet ring

Predominant Pattern/Injury Type

  • Nests, cords, gland-like, tubular, cystic, and plexiform

Predominant Cell/Compartment Type

  • Cuboidal to flat to ovoid with uniform cytology



  • PAS-diastase

    • Reactivity: Negative

  • Mucicarmine

    • Reactivity: Negative


  • Positive for cytokeratin, calretinin, Podoplanin(D2-40), CK5/6, thrombomodulin, WT1

  • Negative for CEA, CD15, MOC-31, EpCAM/BER-EP4/CD326, FXVIIIAg, S100, CD31, CD34, FLI-1


Sex Cord Stromal Tumor

  • Usually intraparenchymal tumor

  • Positive for inhibin and Melan-A(MART-1)

  • Negative for cytokeratin

Malignant Mesothelioma

  • Larger tumor, destructive and infiltrative growth

  • Greater cytologic atypia

Metastatic Signet Ring Cell Carcinoma

  • Clinical history and older age

  • Infiltrative growth, greater cytologic atypia, frequent mitoses

  • Positive for CEA, CD15, EpCAM/BER-EP4/CD326, and MOC-31; negative for calretinin and Podoplanin(D2-40)

Epithelioid Hemangioma/Hemangioendothelioma

  • Vasoformative lesion composed of vacuolated cells

  • Positive for vascular markers (CD31, CD34, FLI-1); negative or weakly/focally positive for cytokeratin

Germ Cell Tumors (Particularly Yolk Sac Tumor)

  • Intraparenchymal mass with heterogeneous appearance

  • Obvious malignant cytologic features

  • Positive for Oct3/4, SALL4, and CD30(BerH2); negative for calretinin

Leiomyosarcoma or Leiomyoma (vs. Leiomyomatous Adenomatoid Tumor)

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Adenomatoid Tumor

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