Index finger acrometastasis: A unique lung cancer case report

Hand metastases are notably rare, comprising around 0.1% of all metastatic diseases, mainly originating from lung cancer, which is responsible for 30-40% of such cases. This report highlights a rare occurrence of distal phalangeal metastasis in a patient with Lynch syndrome, underscoring the diagnostic challenges associated with hand metastases.

A 70-year-old male diagnosed with Lynch syndrome 35 years ago, following colon adenocarcinoma, presented with severe inflammatory lesions on his right index finger. Patient had previous liver segmentectomies to remove metastatic lesions and had multiple cutaneous squamous cell carcinomas in various regions. Recent diagnostics, including a chest CT, identified a thoracic mass suggestive of squamous cell lung carcinoma. Histopathological analysis confirmed the metastasis of lung cancer to the index finger, necessitating a transphalangeal amputation.

Hand metastases are extremely infrequent, often mimicking other conditions and requiring a high index of suspicion for accurate diagnosis. This case reinforces the lung as a frequent origin of hand metastases and the significance of elevated EGFR expression in facilitating metastatic spread.

The rarity of hand metastasis in patients with genetic predispositions like Lynch syndrome calls for heightened vigilance and an integrated management approach. It highlights the critical role of histopathology in diagnosis and the need to consider genetic factors in treatment planning. Further research is encouraged to understand the mechanisms enabling certain cancers to metastasize to the hand and the role of genetic conditions in these processes.