This video features a pathological discussion and microscopic examination of a tissue specimen, which is identified as a classic example of a myofibroma. The discussion focuses on the biphasic nature of the lesion, contrasting the nodular components with the intervening stroma. The nodules, described as "cotton candy colored" (pinkish-purplish), are characterized by bland, spindle to oval cells arranged in fascicles, sometimes appearing plump and exhibiting a pseudo-chondroid or chondromyxoid appearance. Between these nodules are prominent, branching, interconnected vessels described as having a "staghorn" or hemangioparasitic pattern. The cellular areas between the nodules can show brisk mitotic activity but lack significant cellular pleomorphism, indicating a benign nature. The speaker notes that these lesions are classically seen in babies and young children, are usually benign and indolent (sometimes regressing spontaneously), and that standard H&E staining is sufficient for diagnosis, with no special stains typically needed.
Microscopic Review of a Classic Myofibroma
0:00 Specimen Appearance: The specimen is described as large and strikingly "cotton candy colored" (pinkish-purplish/lavender).
0:38 Biphasic Nature: The lesion consists of two main components: nodules and the intervening tissue.
1:14 Nodule Characteristics: The nodules are composed of fibroblasts/spindle to oval cells arranged in fascicles, often compressed between prominent, dilated, branching vessels.
1:40 Vascular Pattern: The branching vessels are noted for their classic "staghorn" or hemangioparasitic appearance, common in various tumors (e.g., solitary fibrous tumors).
2:05 Diagnosis Confirmation (Myofibroma): The speaker confirms the diagnosis is a myofibroma, noting the cells are myofibroblastic (actin positive, usually desmin negative).
3:07 Pseudo-Chondroid Nodules: The nodules are referred to as "pseudo chondroid nodules" due to their bluish, mixoid/chondromyxoid coloration and appearance, which can resemble cartilage.
3:53 Mitotic Activity: The cellular areas between nodules can exhibit brisk mitotic activity, but the cells remain bland and monotonous, lacking pleomorphism.
4:09 Patient Demographics: Myofibromas are classically seen in babies and children, though they can occur in older adults.
4:12 Behavior: These lesions are generally benign, indolent, and may regress spontaneously; recurrence after complete excision is rare.
5:19 Associated Findings: The tumor can sometimes develop focal calcifications or even metaplastic bone.
5:32 Diagnosis Method: The diagnosis is reliably made using standard H&E staining; no special stains are usually required due to the classic appearance.