Abstract Introduction Lung cancer is the leading cause of cancer related death worldwide, with bone metastases occurring in roughly 30 - 40% of all advanced lung cancers. Bone metastases generally involve the axial skeleton and proximal long bones due to their high red marrow content. Acrometastases, metastases to the bones of the hands or feet, account for 1% of all skeletal metastases, while distal appendicular metastases outside the hands and feet, termed mesometastasis, is reported in isolated cases and commonly represents advanced disease. Case description A 67-year-old Caucasian female with a 40 pack-year smoking history and minimal prior medical care presented with right forearm swelling and pain that began after lifting a case of water. Over three months, she developed progressive swelling, pain, and right hand weakness with mild clawing. CT of the forearm revealed complete destruction of the proximal and mid-shaft of the radius with central fluid collection. Incidentally, a right pulmonary mass was seen. CT chest confirmed a right pulmonary mass involving both the upper and lower lobes contiguous with the right hilum in addition with a left mediastinal mass extending into the central left upper and lower lobe. Whole-body bone scintigraphy revealed focal uptake confined to the radial lesion and mild focal uptake of the left sixth and right second ribs corresponding to fractures, with no other osseous involvement. A PET-CT scan subsequently showed no additional areas of abnormal uptake consistent with malignancy. Biopsy of the forearm mass confirmed squamous cell carcinoma of unknown primary. Bilateral hilar lymph node biopsies established pulmonary origin of the cancer. CT Right Upper Extremity: Forearm mass with incidental right lung mass Discussion Metastatic involvement of the radius is rare and seldom occurs as the initial presentation of lung cancer. Previously published cases involved the ulna and occurred in patients with an established diagnosis of lung cancer. In contrast, this patient’s isolated lesion of the radius was the initial clinical manifestation of an otherwise occult malignancy. The absence of additional osseous or visceral metastases on imaging makes this presentation unique, as distal bone metastases typically accompany widespread dissemination. This challenges the conventional understanding that distal appendicular metastases present late in the disease course. Early recognition of atypical metastatic patterns is important to prevent misdiagnosis and avoid delay in identifying primary malignancies. Physicians should consider metastatic disease in the differential diagnosis of solitary bone lesions, especially in patients with significant smoking histories. This abstract is funded by: None
Raghavan et al. (Fri,) studied this question.