Intraosseous Squamous Cell Carcinoma Arising from Chronic Osteomyelitis: A Case Report and Review of the Literature

Chronic osteomyelitis is common in daily practice, but malignant transformation was rare. Hawkins was the first to document the process of squamous cell carcinoma arising in chronic osteomyelitis [1]. The physiopathological mechanism remains unclear. The increased in fistulous discharge, erythematous change, growth of the ulcer may be the red flag signs for malignant transformation. The most definitive surgical treatment in these situations is the limb amputation. We report one case with squamous cell carcinoma arising from a chronic osteomyelitis and discuss through literature review.


Discussion:
Squamous cell carcinoma is the most common type of malignant tumor resulting from chronic osteomyelitis. It usually involves tibia, femur and foot. The mean age was 54~60-year-old, and the interval between onset of osteomyelitis and diagnosis of malignancy was 20~40 years. Symptoms includes local swelling and sinus tract discharge with unpleasant odor. MRI is the useful tool to differentiate the squamous cell carcinoma from other etiologies. Amputation proximal to the neoplasm remain the gold standard for treatment while wide resection is indicated only in selected patients.
Conclusion: Malignant transform from chronic osteomyelitis is a rare lesion in the lower extremities. Surgeon should be aware of the risk of malignant degeneration in patient with osteomyelitis and chronic wound. Early diagnosis and definitive treatment are fundamental for the prognosis and result. hyperplasia with mild atypia. Ten months later, he noticed that the mass regrew and continued to increase in size, causing skin tenting and wound poor healing. Presenting initial chronic osteomyelitis with femur varus deformity and lateral cortex erosion. MRI B.
Presenting left femur osteomyelitis with infectious status of muscle and abscess formation.   X-ray revealed distal femur pathological fracture with varus deformity, B.
Kuntsher nail for internal fixation with vaconcomysin-coated cement, C.
Remove Kuntsher nail and use long cephalomedullary nail.
In order to correct distal femur varas deformity, we performed

Discussion
Squamous cell carcinoma is the most common type of malignant tumor resulting from chronic osteomyelitis [1]. The most common site of involvement is tibia, followed by femur and foot [2,3]. The average age of patients with chronic osteomyelitis related squamous cell carcinoma was 54-60-year-old [3], with male predominance [1,3]. The interval between the onset of osteomyelitis and the diagnosis of malignant transformation was 20~40 years [2,4], with minimum latency period of 20 years or more [3]. In our case, the patient was 68 years of age and the interval was 22 years, which almost compatible with the current report. Chronic osteomyelitis poses a risk of transformation to squamous cell carcinoma. Some author reported that over 25% of malignant tumor arises from chronic infection and inflammation, and 1.6~23% from chronic osteomyelitis [5]. However, the exact mechanism remains unclear and is assumed multifactorial. Squamous cell carcinoma can arise from fistula tract which connects the malignant of epidermal lining.
One hypothesis clarify that inflammatory cytokines may lead to an altered expression of tumor suppression genes causing carcinogenic transformation [6], while other hypothesis clarifies that all cell types in the chronic inflammation may be susceptible to malignant change [4]. The clinical suspicion about malignant transformation including increased in mass size, ulcers, swelling, tenderness, fistula or sinus tract discharge with odor smell, and progressive disabling pain [4,5]. Plain radiography often appears bony erosion, destruction, scalloping, or even pathologic fracture in severe cases. MRI can be useful to differentiate squamous cell carcinoma from other soft tissue tumor [3] and identify adjacent lymphadenopathy. Whole body bone scan can clarify the suspicion of distant metastasis. In our case, MRI revealed lymphadenopathy in the left groin and peri-acetabular region after primary aboveknee amputation. These finding provide us more information on the decision to perform left hemipelvectomy for tumor control.
Most studies declared that amputation is the definitive treatment for carcinomatous transformations of chronic bone infection.
Amputation proximal to the lesion can decrease local recurrence and risk of metastasis, as well as quicker and safer recovery. Wide resection may be one of surgical choices in selected patients, but it's associated with high rate of local recurrence and large skin defects.
Massive soft tissue, muscle, and skin defect can pose a challenge for reconstruction. The distant metastasis and lymphadenopathy had been observed in 10~20% of patients [7], while some report rates more than 40% [6]. Yener et al. report that two patients with malignant lymphadenopathy and distant metastasis all died within one year even under re-amputation [7]. The presence of lymphatic node metastasis or distant metastasis will lower the survival rate and indicate poor prognosis. Diogo et al. [5] mentioned that hemipelvectomy may be required if invasion of lumbar-aortic lymph node. Concerning the high risk of surgery and difficulty in skin coverage, he decided against it. In our case, we performed disarticulation of the hip and lymphadenectomy with care to avoid neurovascular insult, followed by local fasciocutaneous flap for skin coverage. Early recognition and timely therapy are considerably to improve prognosis and decrease the risk of metastasis. Adjuvant chemo radiotherapy is indicated in metastatic patient [5]. In our patients, adjuvant chemotherapy with Cisplatin (75mg/m2) and 5-FU (1000mg/m 2 ) was applied.

Conclusion
Malignant transformation in chronic osteomyelitis is a rare lesion in the lower extremity but unfavorable condition. Early diagnosis and definitive treatment are fundamental for the prognosis and results. Currently, amputation appears to be the gold standard for treatment.