Ossifying fibromyxoid tumor: a clinicopathologic analysis of 26 subcutaneous tumors with emphasis on differential diagnosis and prognostic factors

J Cutan Pathol. 2015 Sep;42(9):622-31. doi: 10.1111/cup.12514. Epub 2015 Jun 11.

Abstract

Introduction: Ossifying fibromyxoid tumor (OFMT) is rare and may present diagnostic difficulty. We describe 26 subcutaneous examples of OFMT emphasizing differential diagnosis and prognostic features.

Methods: Histopathology and follow-up data from archival/consultation cases were reviewed. Prognostic features were assessed according to proposed criteria.

Results: Patients (16 female, 10 male) ranged from 26 to 88 years (median 54). The tumors (median 2.3 cm, range 0.8-8.5) involved lower limb (11), trunk (7), head/neck (4), or arm (4). All showed combinations of corded, nested and trabecular patterns in a fibromyxoid stroma. Out of 26 cases 13 had peripheral ossification. Sixteen of 22 cases showed S100 protein expression. Nuclear grade was low (14); intermediate (8) and high (4) while cellularity was low (14); moderate (7) and high (5), with overall good interobserver agreement. Median mitotic rate was 3/50HPF (0-61). Five met criteria for malignant OFMT showing high nuclear grade or high cellularity and mitotic rate >2/50HPF or both. Thirteen OFMTs were atypical. Follow-up (16/26, median 45.5 months, range 8-108) showed that patients with typical OFMT (3) and atypical OFMT (9) remained disease-free. Three malignant examples of OFMT recurred and one metastasized to the lung. No deaths were recorded.

Conclusions: Our results validate proposed prognostic classification of OFMT. Dermatopathologists should be aware of this unusual superficial tumor given its potentially aggressive behavior.

Keywords: PHF1; malignant; ossifying fibromyxoid tumor; subcutaneous.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Bone Neoplasms / diagnosis
  • Bone Neoplasms / metabolism
  • Bone Neoplasms / pathology*
  • DNA-Binding Proteins / metabolism
  • Diagnosis, Differential
  • Female
  • Fibroma, Ossifying / diagnosis
  • Fibroma, Ossifying / metabolism
  • Fibroma, Ossifying / pathology*
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local / diagnosis
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Staging
  • Observer Variation
  • Polycomb-Group Proteins / metabolism
  • Prognosis
  • Rare Diseases
  • S100 Proteins / metabolism
  • Soft Tissue Neoplasms / diagnosis
  • Soft Tissue Neoplasms / metabolism
  • Soft Tissue Neoplasms / pathology*
  • Subcutaneous Tissue / metabolism
  • Subcutaneous Tissue / pathology

Substances

  • DNA-Binding Proteins
  • PHF1 protein, human
  • Polycomb-Group Proteins
  • S100 Proteins