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 Table of Contents  
Year : 2016  |  Volume : 4  |  Issue : 1  |  Page : 82-84

Myositis ossificans of thigh: Unusual mimicker

Department of Pathology, KS Hegde Medical Academy of Nitte University, Mangalore, Karnataka, India

Date of Web Publication2-Jun-2016

Correspondence Address:
H L Kishan Prasad
Department of Pathology, KS Hegde Medical Academy of Nitte University, Deralakatte, Mangalore - 575 018, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2321-4848.183341

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Metastatic tumors of the intestinal tract from extra-abdominal sites are rare. In cervical cancer, the liver, lung, and the bones are the most common distant sites of metastases. Metastasis to the small intestine is very rare. We report a rare case of metastasis of cervical squamous cell carcinoma to jejunum after a few months of chemoradiotherapy.

Keywords: Myositis, ossification, trauma, zoning

How to cite this article:
Shetty JK, Kishan Prasad H L, Rao C. Myositis ossificans of thigh: Unusual mimicker. Arch Med Health Sci 2016;4:82-4

How to cite this URL:
Shetty JK, Kishan Prasad H L, Rao C. Myositis ossificans of thigh: Unusual mimicker. Arch Med Health Sci [serial online] 2016 [cited 2022 Jun 28];4:82-4. Available from: https://www.amhsjournal.org/text.asp?2016/4/1/82/183341

  Introduction Top

Myositis ossificans (MO) is a localized, nonneoplastic, heterotopic ossification within the muscle. Despite advances in medical imaging, it remains difficult to distinguish it from other disorders such as soft tissue neoplasms. Therefore, a biopsy is frequently performed.[1],[2],[3] We present a rare case of histologically confirmed MO in a 75-year-old male who presented with swelling in the thigh of short duration. The differentiation among MO and its mimics is discussed as well in order to help the clinicians, radiologists, and pathologists to make an appropriate diagnosis.

  Case Report Top

A 75-year-old male admitted for cerebrovascular accident, noticed a recent onset of swelling in the left thigh region. Past history and personal history were both unremarkable. The swelling was firm to hard in consistency measuring 10 cm × 8 cm extending from the gluteal region to the midthigh area. X-ray showed soft-tissue mass with calcified areas. Computed tomography (CT) scan showed large heterogeneous mass in the left thigh with calcified areas and the underlying bone was free from the lesion [Figure 1]a. Fine needle aspiration cytology (FNAC) done outside was reported as soft tissue sarcoma and was suggested for biopsy for confirmation. Hence, core biopsy was done and showed predominant areas of skeletal muscle, fat, and osteocartilaginous fragments with rimming by osteoblasts [Figure 1]b and [Figure 1]c. Osteoblasts showed moderate pleomorphism. Extensive hemorrhagic and fibrotic areas were noted. No evidence of malignancy was detected. Based on these, diagnosis of MO was made. The patient was treated with anti-inflammatory drugs and was closely monitored. After 1 year of follow-up, swelling gradually regressed in size.
Figure 1: (a) CT showing large heterogeneous mass in the left thigh with calcified areas (b and c) histopathology showing myositis ossificans comprising muscle, bone, and fatty tissue [Hematoxylin and Eosin, 100×]

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  Discussion Top

“MO” is a benign ossifying process occurring most commonly in the muscle or sometimes in other soft parts.[1],[3],[4] This is a rare condition with distinct clinical, radiological, and pathological features. It is of unknown etiology, occurs after damage to muscles with subsequent proliferation of connective tissue and differentiation into mature bone. The tissue necrosis leads to heterotrophic fibroblastic and vascular proliferation with eventual ossification.[2],[3],[5],[6] Trauma has been associated with the majority of cases, although there are reported cases without an antecedent injury. The most reported risk factor is re-injury during the early stages of recovery.[1],[4]

Many clinicopathologic entities have been included in MO.[3],[4] They are:

  1. Myositis ossificans progressiva (MOP), which occurs in early life, progressively affects all skeletal muscles, and leads to death,
  2. MO traumatica which follows trauma or surgical operations such as abdominal incision, orthopedic operation, and dislocation,
  3. MO associated with neuromuscular and chronic disease such as tetanus, poliomyelitis, paraplegia, or burns, and
  4. Nontraumatic MO occurring in those with no definitive causative factor.

The MO traumatica is further divided into two forms: One following severe trauma and the other, simple osseous formation appearing in the sites of repeated slight injuries or irritation. Spontaneous ossification with specific deformities of big toes is frequently seen. The MO circumscripta and traumatica ossification are seen following mild or significant trauma, occurs as single, nonrecurring lesion. MOP is characterized by progressive replacement of muscles, tendons, ligaments, fascia, and aponeurosis by bone leading to progressive stiffness of the adjacent joints and particularly the chest wall leading to pneumonia and death. The presence of type I collagen in these tissues probably determines its eventual ossification. Congenital abnormalities such as short and stiff great toes, short broad femoral neck, exostoses of proximal tibia and abnormal cervical vertebrae with small bodies, large pedicles, and large spinous processes. Other associated problem includes deafness in 25% of cases.[3],[4],[5],[6]

The disorder usually manifests in the early age group and occurs commonly in the neck (50%), dorsal paraspinal region (30%), head (10%), or limbs (10%). 70% develop temporomandibular joint ankylosis that leads to death by starvation.[3],[6] Other rare sites include joint capsules, ligaments, and plantar fascia. However, connective tissue of facial and extraocular muscles, intestines, tongue, larynx, and skin are spared.[4],[5],[6]

The histopathology of MO shows osteoid like an osteosarcoma. The proliferating, immature fibroblasts with hyperchromatic nuclei can mislead to sarcomatous changes.[2],[4],[6] The “zoning phenomenon” — A central layer of cells and a peripheral layer of natural osteoid is the most important feature for differentiating pseudomalignant MO from osteosarcoma. Evidence of the zoning phenomenon in histopathology correlated with clinical and radiological findings to avoid a misdiagnosis of this condition.[3],[5],[6] Painless, slow progression of the lesion without early calcification is suggestive of a nonmalignant tumor.[2],[4]

Surgical removal of the extra new bone is not helpful as reformation of the myositic bone occurs within a short time.[3],[5],[6] Physiotherapy and change in the type of work can be advised. Numerous drugs have been tried without much success. Although pseudomalignant MO and soft tissue sarcomas resemble each other clinically and pathologically, the treatment approach for this condition differs greatly. Clinical, radiological, and histopathological evaluation should be performed and the findings considered, carefully avoiding unnecessarily aggressive treatment of pseudomalignant MO.[1],[3],[6]

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Conflicts of interest

There are no conflicts of interest.

  References Top

Ragunanthan N, Sugavanam C. Pseudomalignant myositis ossificans mimicking osteosarcoma: A case report. J Orthop Surg (Hong Kong) 2006;14:219-21.PORT  Back to cited text no. 1
Lungu SG. Myositis Ossificans - Two case presentations. Medical J Zambia 2011;38:25-31.  Back to cited text no. 2
Carlier RY, Safa DM, Parva P, Mompoint D, Judet T, Denormandie P, et al. Ankylosing neurogenic myositis ossificans of the hip. An enhanced volumetric CT study. J Bone Joint Surg Br 2005;87:301-5.  Back to cited text no. 3
Sakhalkar VS, Dalvi RB, Pradhan MR, Colaco MP, Merchant RH. Myositis ossificans progressiva. Indian Pediatr 1994;31:1413-5.  Back to cited text no. 4
Wang XL, Malghem J, Parizel PM, Gielen JL, Vanhoenacker F, De Schepper AM. Myositis ossificans cirmcumscripta. JBR-BTR 2003;86:278-85.  Back to cited text no. 5
Martin DA, Senanayake S. Images in clinical medicine. Myositis ossificans. N Engl J Med 2011;364:758.  Back to cited text no. 6


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