This video details the histological features of Elastic Fibroma Dorsi (Elastofibroma Dorsi), a benign and distinctive soft tissue entity. Histologically, the lesion appears bland at low power, consisting of mature adipose tissue interspersed irregularly with dense, hypocellular bundles of fibrocollagenous tissue. The diagnostic hallmark, visible at higher magnification, is the presence of numerous, large, abnormal elastic fibers which display a characteristic refractile "flower" or "daisy" morphology in cross-section, and a "beads on a string" or "caterpillar" appearance when cut longitudinally. The lesion is almost exclusively found deep to the inferior tip of the scapula in older women, suggesting it is a reactive process caused by chronic repetitive motion and wear and tear. While diagnosable on H&E stain, its unique elastic component is dramatically highlighted by special stains like Verhoeff-Van Gieson (VVG).
Summarizing Elastic Fibroma Dorsi: A Pathology Review
[0:04] Introduction: Elastic Fibroma Dorsi (Elastofibroma Dorsi) is presented as a benign, rare, and visually distinctive entity.
[0:16] Low Power Appearance: The lesion is often nonspecific and bland, consisting of mature adipose tissue (fat) irregularly mixed with dense, hypocellular fibrocollagenous tissue (dense pink collagen). It might initially be mistaken for a scar or reactive fibrosis.
[1:23] Key Diagnostic Feature: The crucial component is the unique background matrix: large, irregular elastic fibers interspersed between the bundles of dense collagen.
[1:47] Microscopic Morphology (Cross-Section): By adjusting the microscope condenser, the fibers become highly refractile. When cut in cross-section, they resemble "beautiful little flowers" or "daisies" with tiny petals.
[2:05] Microscopic Morphology (Longitudinal Section): When cut longitudinally, these fibers appear as "little beads on a string" or "caterpillars."
[2:28] Classic Location and Patient Profile: This lesion occurs almost exclusively at the inferior tip of the scapula, deep to the scapula (between it and the underlying ribcage). It usually affects adult women over 50.
[3:06] Etiology: The mass can be bilateral and is thought to be a reactive process rather than a true tumor, likely resulting from chronic wear and tear or repetitive motion of the scapula against the rib cage.
[4:05] Clinical Significance: The location is so characteristic that experienced orthopedic surgeons may recognize the ill-defined mass clinically and radiologically, potentially avoiding a biopsy.
[5:04] Special Stains: While diagnosis can be made on H&E, an elastin stain (like VVG) will turn the abnormal elastic fibers black, making the characteristic "caterpillar" and "flower" structures stand out beautifully [7:09].
[5:37] Differential Diagnosis: Other bland, hypocellular fibrous lesions like Gardiner fibroma or nodular fasciitis should be considered, but they lack the distinct elastic fiber bundles seen in Elastofibroma Dorsi.