Penis & scrotum

Other tumors


Last author update: 16 May 2023
Last staff update: 16 May 2023

Copyright: 2022-2023,, Inc.

PubMed Search: Myointimoma

Khaled Sabry Mohamed, M.D.
Samer Z. Al-Quran, M.D.
Page views in 2022: 76
Page views in 2023 to date: 475
Cite this page: Mohamed KS, Al-Quran SZ. Myointimoma. website. Accessed September 26th, 2023.
Definition / general
  • Benign myointimal proliferation with predilection to the corpus spongiosum of the glans penis
Essential features
  • Benign mesenchymal neoplasm in the corpus spongiosum of the glans penis
  • Intravascular proliferation of the vascular intimal cells
  • Lesional cells stain with α smooth muscle actin but not desmin
  • Penile myointimoma
  • Myointimoma of the penis
ICD coding
  • Corpus spongiosum of the glans penis
  • Intravascular proliferation from the intimal cells of the inner layer of the corpus spongiosum vasculature in the glans penis (Am J Surg Pathol 2000;24:1524)
Diagrams / tables

Images hosted on other servers:

Anatomy of corpus spongiosum in glans penis

Histology of intima

Clinical features
Prognostic factors
Case reports
  • Simple excision
Clinical images

Images hosted on other servers:

Nodule on the left side of glans penis

Gross images

Images hosted on other servers:

Excised nodule

Frozen section description
Microscopic (histologic) description
  • Multinodular or plexiform pattern; composed of occlusive intravascular myointimal proliferation (Am J Surg Pathol 2000;24:1524)
  • Nodules contain spindle or stellate shaped cells embedded in abundant fibromyxoid matrix or sometimes chondroid matrix (Am J Surg Pathol 2007;31:1622)
  • Cells have long eosinophilic cytoplasmic processes, blunt ended nuclei, fine chromatin and juxtanuclear vacuoles
  • Foci of degenerative changes appear as ghost cells (Am J Surg Pathol 2000;24:1524)
  • No cytologic atypia, nuclear pleomorphism, prominent nucleoli or mitoses
  • Residual smooth muscle bundles surrounding the tumor (Actas Dermosifiliogr 2009;100:511)
  • Overlying skin may show slight hyperkeratosis (J Cutan Pathol 2009;36:817)
  • No necrosis or significant inflammation
Microscopic (histologic) images

Contributed by Maria Tretiakova, M.D., Ph.D.

Plexiform architecture

Intravascular proliferation

Intravascular intimal proliferation

Fibromyxoid stroma

Bland myofibroblastic cells

SMA staining

Negative stains
Sample pathology report
  • Glans penis, excisional biopsy:
    • Penile myointimoma (see comment)
    • Comment: Sections show a plexiform vascular proliferation composed of spindle cells in a fibromyxoid background with occluded lumens. The neoplastic cells are α smooth muscle actin positive and desmin negative.
Differential diagnosis
  • Plexiform fibrohistiocytic tumor:
    • Not intravascular
    • Common in extremities, trunk, head and neck
    • Dimorphic population of cells:
      • Fascicles of spindle cells with no desmin reactive collarettes of residual native smooth muscles, which are seen in myointimoma
      • Nodules of histiocytes, including osteoclast-like giant cells (CD68+ and CD163+)
  • Epithelioid hemangioendothelioma:
    • Neoplastic cells are more epithelioid with intraluminal vacuoles instead of intracytoplasmic juxtanuclear vacuoles
    • CD34+, CD31+ and SMA-
  • Myofibroma:
    • Biphasic pattern of myoid nodules similar to myointimoma; however, there are hemangiopericytoma-like areas
    • Can involve vessels but is not limited to intravascular lumina
  • Intravascular fasciitis:
    • May overlap
    • Intralesional inflammatory cells, mucoid pools
  • Nerve sheath tumor:
    • Diffuse nuclear S100
  • Leiomyoma:
    • Not intravascular
    • Fascicular architecture not plexiform or multinodular pattern
    • Fibromyxoid stroma is not a typical feature
    • SMA+ and desmin+
Board review style question #1

The tumor in the image shown above is found in the penis corpus spongiosum. What is your diagnosis?

  1. Epithelioid hemangioendothelioma
  2. Leiomyoma
  3. Myointimoma
  4. Myofibroma
Board review style answer #1
C. Myointimoma

Comment Here

Reference: Myointimoma
Back to top
Image 01 Image 02