title: Intramuscular hemangioma causing periosteal reaction and cortical hypertrophy misdiagnosed as osteoid osteoma.
abstract: BACKGROUND
  Intramuscular hemangioma in the periosteal region is rare. Although comprising less than 1% of all hemangiomas, they represent the most common type of intramuscular tumors. When located adjacent to bone, a periosteal reaction can occur. The deep localization of the hemangioma poses the diagnosis difficult. Only 8% to 19% of cases were diagnosed before surgery according to the literature review.
  
  
  METHODS
  We present a case of forty-one-year-old female diagnosed with intramuscular hemangioma, mimicking osteoid osteoma, adjacent to the periosteal region of tibia diaphysis treated by surgical excision.
  
  
  CONCLUSIONS
  When intramuscular hemangioma occurs nearby a bone structure, it can cause cortical, medullary and periosteal bone changes that are frequently misdiagnosed by plain radiography. Due to their infrequency, deep location, and atypical presentation, these lesions are seldom diagnosed at presentation. The hemangioma of the periosteal region can be locally destructive due to compression exerted on neighboring structures. It does not regress spontaneously, and surgical excision is frequently needed.
  
  
  CONCLUSIONS
  Intramuscular hemangioma of periosteal region occurs most commonly adjacent to long bones of the lower limb. They can cause hypertrophic periosteal reactions mimicking a periosteal or parosteal tumor. Although osteoid osteoma was considered in the differential diagnosis, MRI with enhancement should be performed to exclude intramuscular hemangioma. This may avoid unnecessary aggressive en-bloc tumor excisions resulting in bone weakness and prolonged rehabilitation. This case report has been written in line with the SCARE criteria (Agha et al., 2016 [1]).
authors.affiliation: Department of Orthopedics, Hsinchu Mackay Memorial Hospital, Hsinchu City, Taiwan. Electronic address: yalinyeh2004@yahoo.com.
authors.forename: Ya-Lin
authors.initials: YL
authors.lastname: Yeh
authors.affiliation: Department of Ophthalmology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Shu-I
authors.initials: SI
authors.lastname: Yeh
authors.affiliation: Department of Orthopedics, Hsinchu Mackay Memorial Hospital, Hsinchu City, Taiwan.
authors.forename: Chih-Ting
authors.initials: CT
authors.lastname: Cheng
keywords: Intramuscular hemangioma; Osteoid osteoma; Periosteal reaction