Differential Diagnosis of Hand Masses: Clinical Implications of a Tenosynovial Tumor Mimicking a Synovial Cyst

Abstract

Localized tenosynovial giant cell tumor (TGCT) is one of the most common benign neoplasms of the hand, often mimicking cystic lesions and posing diagnostic challenges in orthopedic practice. The aim of this study is to describe a clinical case and analyze the implications of differential diagnosis in soft tissue masses. A 51-year-old female patient presented with a space-occupying lesion in the right middle finger, initially suspected as a synovial cyst. During surgical excision, a solid mass was identified, and histopathological and immunohistochemical evaluation confirmed a localized TGCT, with positivity for CD45 (70%) and CD68 (20%) and absence of malignancy markers. This case highlights that isolated clinical interpretation may lead to diagnostic bias, emphasizing the importance of complementary studies. As a limitation, this is a single-case descriptive study. It is concluded that clinicopathological and immunophenotypic integration improves diagnostic accuracy, guides surgical management, and reduces recurrence risk.