A 56-year-old Caucasian male presented to the emergency department with progressively worsening pain, erythema, and swelling of the left hallux after trauma resulting in loss of the nail bed one month prior to presentation. He developed a dorsal wound with purulent green discharge and an inability to bear weight. He denied other complaints. His past medical history was significant for hypertension. He denied any surgical history or drug allergies. His medications consisted of losartan 50 mg daily and atenolol 25mg daily. He admitted to smoking 1 pack per day for 15 years, occasional alcohol use and no recreational drugs. On presentation his vitals were stable and the exam showed erythema and edema of the left hallux with a dorsal wound over the nail bed. There was positive probe to bone with expression of green purulent material. Sensation and pulses were grossly intact bilaterally. Laboratory findings included total leukocyte count of 8,800/mm3, erythrocyte sedimentation rate (ESR) of 8 mm/hr and c-reactive protein (CRP) measuring 6.5 mg/L. X-ray of the foot showed cortical thinning with demineralization along the lateral aspect of the first proximal phalanx suggesting osteomyelitis. MRI of the foot showed phlegmonous soft tissue and fluid loculation measuring 17mm x 10mm x16mm with erosion of adjacent cortex. Given peculiar MRI findings, the patient was referred for bone biopsy for definitive diagnosis, which showed well-differentiated squamous cell carcinoma (SCC) invading bone.
Cutaneous SCC is the second most common cancer affecting Caucasians, with an incidence of around 200,000 every year in the United States. It can develop in chronically diseased skin or in the absence of any precursor lesion. Metastatic disease is uncommon however the likelihood increases with involvement of nearby bone, nerve or muscle. Our patient’s clinical findings and initial imaging suggested osteomyelitis (OM) however given a lack of abnormal laboratory markers (no leukocytosis, normal ESR/CRP) a bone biopsy was obtained which showed primary SCC. Given the high potential for extensive tissue destruction and distant metastasis, these biopsy findings warranted surgical removal. We have described an unusual case of primary SCC invading bone in the absence of OM.
Bone biopsy is the gold standard for a definitive diagnosis of osteomyelitis. To provide appropriate care, it is important such lesions are biopsied as sometimes it is difficult to differentiate solely based on clinical or radiographic findings. This case highlights the importance of including primary SCC on the differential when evaluating suspicious lower extremity lesions. Early recognition and confirmatory diagnosis by biopsy can prevent distant metastasis and improve prognosis.