Soft tissue
Mesenchymal tumors

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 19 September 2016, last major update November 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Mesenchymoma [title]

Cite this page: Mesenchymoma. website. Accessed October 27th, 2016.
Definition / General
  • Tumors composed of two or more different histological mesenchymal elements
  • See also description in bone or eye chapters
  • May be benign or malignant

AFIP Third Fascicle and WHO dislike this terminology, and recommend:
  1. Describing as mixed mesenchymal neoplasm and specifying the components or
  2. Classifying based on predominant mode of differentiation and mentioning the other component(s)

Benign mesenchymoma
  • Tumors composed of two or more different histological benign mesenchymal elements
  • See also description in bone or eye chapters
  • Also called hamartoma, but mesenchymal hamartoma of liver (also called mesenchymoma) is a different entity
  • Most frequent type is angiomyolipoma, which is described separately
  • May recur if inadequately excised

Malignant mesenchymoma
  • Rare tumors with two or more sarcomatous elements, including osteosarcoma, chondrosarcoma, leiomyosarcoma, rhabdomyosarcoma and liposarcoma
  • Each element must be sufficiently differentiated to clearly recognize its histogenic type
  • Cannot count fibrosarcoma as one of the elements since these areas are present in most sarcomas
  • Excludes dedifferentiated liposarcoma, dedifferentiated chondrosarcoma, malignant Triton tumor and myoblastic differentiation in liposarcoma or chondrosarcoma
  • First described by Stout in 1948 (Ann Surg 1948;127:278)
  • According to Harry Evans, do not form a distinct clinicopathologic entity and should be classified in other ways (Fletcher: Pathology and Genetics of Tumours of Soft Tissue and Bone, 3rd Edition, 2006)
Benign mesenchymoma
  • Frequently in retroperitoneum or chest wall
Prognostic Factors
Malignant mesenchymoma
  • Usually high grade and aggressive (Cancer 1996;77:467)
  • Frequently recurs (2/3), metastasizes (1/3) and causes death (50%)
  • Poor prognostic factors: age < 40 years, rhabdomyosarcomatous component (Oncol Rep 2003;10:803)
  • Must sample generously to find various components and rule out dedifferentiated tumors
Case Reports
Benign mesenchymoma
Malignant mesenchymoma
Malignant mesenchymoma
  • Complete resection
Gross Images

Images hosted on other servers:
Malignant mesenchymoma:

Deep gluteal muscles

Rectus femoris muscle

Micro Images

Images hosted on other servers:
Benign mesenchymoma:

Stomach tumor

Dense fibrous tissue, woven bone and cartilage like areas

Loose vascular mesenchyme, smooth muscle and fat

Malignant mesenchymoma:

Pleural tumor

Deep gluteal tissues

Rectus femoris muscle

Anterior thigh muscles


Deep tissues in lateral neck




Spindle cell component

Chondrosarcoma region

Area of bone formation