Atypical glomus tumors of the lower extremity: a case report of two patients.

Introduction and importance: Glomus tumors are rare but clinically significant neoplasms characterized by severe focal pain and a broad anatomic distribution extending well beyond the digits. Extradigital glomus tumors are rare and can lead to prolonged pain and treatment delays; hence, the aim of this study. Case presentation: Patient A, a 51-year-old male, experienced 12 years of refractory anterior right hip pain. MRI revealed an intermediate signal intensity lesion near the intertrochanteric region. Patient B, a 48-year-old male, had 5 years of knee pain with quadriceps atrophy secondary to an adductor canal lesion on MRI. Histopathology revealed uniform, small, round-to-oval cells with a cookie-cutter appearance and pale eosinophilic cytoplasm, which were highly vascular and stained positive for smooth muscle actin. Treatment involved marginal surgical excision, with no signs of recurrence on prolonged follow-up. Clinical discussion: Diagnosis relies on clinical awareness and suspicion, especially in non-resolving and atypical causes of pain and functional limitation, in combination with targeted imaging and confirmatory histopathology. The immunophenotype is crucial in distinguishing a glomus tumor from numerous mimickers. Surgical excision remains curative in most cases, although recurrence can occur when resection is incomplete. Awareness of atypical variants and malignant glomus tumors is essential to ensure proper and timely management. Conclusion: Extradigital, deep-seated glomus tumors are atypical, leading to prolonged diagnostic delays. The diagnostic challenges of extradigital glomus tumors underscore the need for clinical vigilance and timely surgical management.