44 years old male with painful swelling of the right subscapular region

Case provided by Tilmann

History
44 years old male with a slightly painful swelling of the right subscapular region since approximately one year. The patient showed no erythema or other signs of infection.

Imaging findings
MRI of the right thoracic wall shows an ill-defined, lenticular, uncapsulated, heterogeneous mass of 8,6 cm, slightly elevating and displacing the serratus anterior muscle ventrally (A, pre-contrast transverse T1wi). The lesion has hypointense to intermediate signal intensity in T1-weighting (A). Most of the mass has a signal intensity similar to that of skeletal muscle and fewer parts have some heterogeneous hyperintense signals in T2 weighting (B. transverse T2wi). After contrast media application the lesion shows faint heterogeneous enhancement (C). In a second MRI of the contralateral thoracic wall a similar, slightly smaller lesion in the same location with the same morphology and signal intensity is found.

Diagnosis
Bilateral Elastofibroma.

Discussion
Elastofibroma, also called elastofibroma dorsi, is a rare benign fibroelastic tumor-like condition made up of enlarged and irregular elastic fibers. Patients are usually elderly (mean age 65-70 years) with predominance of the female gender (5:1). In most cases it is unilateral, but in up to 10% it occurs bilaterally.

The pathogenesis is not clear and theories about its origin include a genetic predisposition, repeated trauma and friction, and enzymatic defects resulting in abnormal elastogenesis (if occurring multifocal).

Patients present with a slow growing deep-seated firm mass. Fare more than 50% of elastofibromas are asymptomatic, but there may be pain or tenderness in some cases. By microscopic view, there is an admixture of heavy dense bands of collagenous tissue with interspersed fat dissected and abnormal elastic fibers.

The tumors usually range about 5 cm in size, but have been reported to be as large as 20 cm.

The top differential diagnosis includes soft tissue sarcomas (similar CT and MRI appearance, unilateral, may invade adjacent structures), Ewing sarcoma family of tumors (unilateral, children or young adults), desmoid-type fibromatosis and metastasis (most common in melanoma, often multiple masses). Especially bilaterality helps eliminate sarcoma from further consideration.

Simple excision is the treatment of choice. Isolated recurrences may be seen, but there is no malignant potential.

 Teaching points

  • Elastofibroma is a rare and benign tumor usually seen in elderly patients with predominance in women.
  • It can be difficult to differentiate it from soft tissue sarcoma or other malignancies.
  • Bilateral occurrence (10% of patients) helps to rule out sarcoma from differential diagnosis.

Recommended reading

Jürgen Freyschmidt
Skeletterkrankungen: Klinisch-radiologische Diagnose und Differentialdiagnose
Springer Verlag 2016.

Chandrasekar et al.
Elastofibroma Dorsi: An Uncommon Benign Pseudotumour.
Sarcoma. 2008; 2008: 756565

Ochsen et al.
Best Cases from the AFIP: Elastofibroma Dorsi
Radiographics. 2006; 26 (6): 1873–1876.

 

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