This video features a pathology case presentation focusing on a highly cellular vascular lesion in an infantile patient, diagnosed as Infantile Hemangioma (IH), previously known as cellular cavernous hemangioma of infancy. Microscopically, the lesion displays a distinct, lobulated or plexiform architecture, comprising innumerable tiny, monotonous vascular spaces lined by endothelial cells. A crucial diagnostic feature highlighted is the lesion's expansive growth pattern, which fills dermal and subcutaneous spaces while leaving pre-existing adnexal structures (such as eccrine coils and hair follicles) intact. The discussion also covers immunohistochemical confirmation, noting that IH is uniquely positive for GLUT-1 in the endothelial cells, distinguishing it from nearly all other vascular anomalies. The presenters briefly touch upon the current trend toward medical treatment (e.g., beta-blockers) over large surgical excisions.
Microscopic Features and Diagnosis of Infantile Hemangioma
0:06 Initial Appearance: The lesion is highly cellular, characterized by numerous, large vascular channels and a densely packed overall appearance.
0:33 Architectural Pattern: The low-power view reveals a distinct "plexiform" or "interwoven lobular" arrangement, where multiple interconnected lobules fill the excision site.
0:50 Cellular Detail: Closer inspection shows the lobules are composed of innumerable, tiny, jam-packed vascular spaces lined by monotonous endothelial cells, lacking atypia.
1:34 Diagnosis: The lesion is identified as Infantile Hemangioma (IH), noting that the name "cellular cavernous hemangioma of infancy" is an older term. The appearance, while distinct, can be mistaken for something malignant due to its high cellularity.
2:02 Sparing of Adnexal Structures (Key Takeaway): A significant finding is that the lesion fills all spaces but leaves pre-existing structures (like eccrine ducts, coils, and hair follicles) intact, growing around them rather than destroying them.
2:34 Proliferating Phase: In the earliest, proliferating phase, the capillaries can be so tightly packed that the lesion appears solid, making the vascular spaces difficult to discern.
3:14 Immunohistochemistry for Structure: The presenter notes that markers like CD31 (endothelium) and smooth muscle actin (pericytes/modified smooth muscle cells) can reveal the underlying organization of the capillaries and the presence of pericytes filling the space between the tiny vessels, proving the organized, benign nature of the growth.
4:07 Unique GLUT-1 Positivity (Key Takeaway): IH is unique among vascular lesions because its endothelial cells stain positive for GLUT-1 (Glucose Transporter 1). Most other vascular lesions are negative. Normal red blood cells also stain, providing a helpful internal control, but this requires careful interpretation.
5:01 Clinical Context and Treatment: Infantile Hemangiomas usually affect babies and often regress spontaneously, though variable amounts can persist. Due to the rise of medical therapies (like beta-blockers), large surgical excisions of IH are seen less frequently in pathology practice today.