Not Just a Lipoma: A Soft Tissue Mass with Aggressive Pathology

Document Type

Conference Proceeding - Restricted Access

Publication Date

5-8-2026

Abstract

Soft tissue masses are commonly encountered in primary care, with most representing benign entities such as lipomas. In contrast, soft tissue sarcomas are rare, accounting for less than 1% of all adult malignancies. Within this category, spindle cell sarcomas comprise a diverse subgroup with variable histology, behavior, and prognosis. These tumors often develop insidiously and may initially evade detection by ultrasound, particularly when arising from deep muscle layers. Differentiating benign soft tissue lesions from aggressive sarcomas remains a diagnostic challenge. Delayed recognition can result in extensive local spread requiring complex, multidisciplinary treatment.

A 65-year-old male with a history of type 2 diabetes mellitus, hypothyroidism, hyperlipidemia, and prior lumbar spine surgery presented to primary care with several weeks of worsening pain in his right shoulder and upper back. An Initial ultrasound revealed asymmetric subcutaneous fat without any clearly defined mass or fluid collection, suggesting a benign process. Over two months, the patient experienced rapid growth of a firm and painful mass in the right scapular region. MRI of the chest identified a large right paraspinal mass centered in the upper back musculature with invasion of the T2 vertebral body, neural foramen, ribs, and epidural space. The differential diagnosis included lipoma, atypical lipomatous tumor, malignant peripheral nerve sheath tumor, leiomyosarcoma, and dedifferentiated liposarcoma.

Spindle cell sarcomas are rare and aggressive malignancies, with prognosis depending on tumor size, grade, ability to resect, and extent of local invasion. This case highlights the diagnostic limitations of ultrasound in detecting deep soft tissue masses and underscores the importance of maintaining suspicion when presumed lipomas exhibit rapid growth, firmness, or persistent pain. Early use of advanced imaging and multidisciplinary referral are essential to optimize treatment options and prognosis for patients with uncommon but high-risk soft-tissue sarcomas.

Comments

2026 Research Day Corewell Health West, Grand Rapids, MI, May 8, 2026. Abstract 2074

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