Are You Confident of the Diagnosis?
What you should be alert for in the history
Lesions are typically seen in adults.
Characteristic findings on physical examination
Characteristic finding is a low-growing asymptomatic soft subcutaneous solitary nodule, most commonly in the subcutaneous tissue of the posterior neck, shoulder, and back.
Expected results of diagnostic studies
Histopathology demonstrates an accumulation of normal-appearing mature adipose intermixed with spindle cells (Figure 1, Figure 2).
Computed tomagraphy (CT) scans reveal homogenous low-density areas, intermixed with higher density areas, which correlate with spindle cells accumulations. Magnetic resonance imaging (MRI) yields a better tissue deliniation and extent of the tumor.
Classic lipomas are not otherwise histologically associated with the accumulation of spindle cells.
Epidermal inclusion cysts demonstrate an overlying punctum, are less stable in size, and are histologically distinct.
Pilar cysts are usually on the scalp, presenting as marble-like nodules that histologically distinct.
Angioleiomyomas are histologically distinct, as are subcutaneous neurofibromas, subcutaneous dermatofibromas, neurilemmomas, rheumatoid nodules (associated with rheumatic disease), pseudorheumatoid nodule/deep granulare annulare, subcutaneous sarcoidosis, abscesses, and hematomas (usually associated with trauma).
Who is at Risk for Developing this Disease?
The typical patient is a 45- to 65-year-old male (the latter in about 91% of cases)
What is the Cause of the Disease?
Lesions result from an accumulation of spindle cells, with or without fat accumulation, associated with chromosomal rearrangements of 13q and 16q.
Systemic Implications and Complications
Occasionally, spindle cell lipomas may be in unusual areas. An esophageal spindle cell lipoma has been reported to result in dysphagia, weight loss, and near asphyxiation when the pedunculated mass was aspirated.
Optimal Therapeutic Approach for this Disease
If treatment is desired, surgical excision is the optimal treatment.
Reassure the patient that these are benign lesions that can be excised if desired.
Unusual Clinical Scenarios to Consider in Patient Management
There is a concern that some cases of pleomorphic lipoma (pseudosarcomatous variant of spindle cell lipoma) may actually represent liposarcoma, especially if situated deep in tissue (Figure 3). Otherwise, they are benign and behave like spindle cell lipomas.
What is the Evidence?
Pandya, KA, Radke, F. “Benign skin lesions: lipomas, epidermal inclusion cysts, muscle and nerve biopsies”. Surg Clin N Am. vol. 89. 2009. pp. 677-87. (Review of lipoma and epidermal inclusion cysts, including workup and treatment)
Bancroft, LW, Kransdorf, MJ, Peterson, JJ, O’Conner, MI. “Benign fatty tumors: classification, clinical course, imaging appearance, and treatment”. Skeletal Radiol. vol. 35. 2006. pp. 719-33. (Review of different fatty tumors, with special discussion of imaging findings)
Azzopardi, JG, Iocco, J, Salm, R. “Pleomorphic lipoma: a tumour simulating liposarcoma”. Histopathology. vol. 7. 1983. pp. 511-23. (Review of pleomorphic lipoma)
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