Penis and scrotum
Benign tumors
Myointimoma

Authors: Antonio Cubilla, M.D., Alcides Chaux, M.D. (see Authors page)

Revised: 3 April 2018, last major update May 2010

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PubMed Search: Myointimoma

Cite this page: Cubilla, A., Chaux, A. Myointimoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/penscrotummyointimoma.html. Accessed July 21st, 2018.
Definition / general
  • Benign myointimal proliferation with myxoid phenotype, exclusively affecting corpus spongiosum of glans penis
Epidemiology
Sites
  • Glans
Etiology
  • Unclear if reactive or neoplastic
Clinical features
  • Small palpable nodular lesion on glans
  • No recurrences reported, even in incomplete resections
Case reports
Treatment
  • Conservative local excision
  • Does not recur, even after incomplete excision
Gross description
  • 0.5 - 2 cm mass
Microscopic (histologic) description
  • Plexiform / multinodular pattern of growth
  • Exclusive intravascular growth extending through vascular spaces of corpus spongiosum
  • Atrophy of preexisting vessel walls and loss of vascular lumina
  • Spindle and bland appearing tumor cells with eosinophilic cytoplasm and indistinct cell borders (myofibroblast appearance)
  • Intracytoplasmic vacuoles are common
  • Surrounding stroma frequently showing myxoid / fibrotic changes
  • Residual smooth muscle at the tumor periphery
  • Also areas of degenerative changes with "ghost cell" morphology
Microscopic (histologic) images

Images hosted on other servers:

Complex myointimal
proliferation
involving the corpus
spongiosum

Increase in
intravascular spindle
cell buds on a
fibromyxoid matrix

Negative stains
Differential diagnosis
  • Angioleiomoyoma (vascular leiomyoma): usually women, not in penis, often painful and smooth muscle cells surrounding vascular lumina
  • Epithelioid hemangioendothelioma: very similar in morphology, very uncommon in penis, positive for CD31 and CD34
  • Leiomyoma: predominant fascicular pattern of growth, rarely plexiform / multinodular, infrequent myxoid changes, desmin+
  • Myofibroma: usually before age 2; does not affect penis; spindle cells arranged around thin walled branching vessels resembling hemangiopericytoma; usually calcification, necrosis
  • Nerve sheath tumors (neurofibroma, schwannoma, nerve sheath myxoma): very uncommon in penis, less condensed myxoid matrix and positive for S100
  • Nodular fasciitis, intravascular, late stage: intralesional inflammatory cells, expansion of vascular spaces, osteoclast-like giant cells and acellular mucoid pools
  • Plexiform fibrohistiocytic tumor: usually women, extravascular, deep dermal or subcutaneous tumor with ray-like extension into skeletal muscle or adipose tissue, spindle cells admixed with nodules of histiocytic cells and occasional osteoclast-like giant cells