Proximal Epithelioid Sarcoma Mimicking Inguinal Inflammation.

Area of Science:

• Oncology
• Pathology

Background:

• Epithelioid sarcoma (ES) is a rare soft tissue sarcoma with classic and proximal subtypes.
• Proximal ES typically affects older adults, occurring in deep tissues near the body's core, and is often large.

Purpose of the Study:

• To report a unique case of a very small proximal epithelioid sarcoma in the inguinal region.
• To discuss the diagnostic challenges posed by small, atypical proximal ES presentations.

Main Methods:

• Case presentation of a patient with a painful inguinal mass.
• Diagnostic workup included magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT).
• Incisional biopsy and subsequent wide excision with pathological examination.

Main Results:

• The small size and internal signal patterns on MRI mimicked inflammatory lesions like lymphadenitis.
• Despite initial monitoring, the mass progressed, leading to biopsy and suspicion of ES.
• Pathological examination confirmed proximal ES with clear surgical margins; no metastases were detected by PET-CT.

Conclusions:

• Small proximal epithelioid sarcoma can present atypically, challenging clinical and imaging diagnoses.
• The broad differential for inguinal masses underscores the critical role of pathological evaluation via biopsy to avoid diagnostic errors.