- Overlying epithelium is of St.Squamous epithelium and is flat devoid of rete pegs.
- Connective tissue contains bundles of collagen fibres interspersed with many fibroblasts and blood vessels.
- Inflammatory cell infiltate present in cases of infection and trauma.
- It is composed of mature adipocytes mixed with connective tissue septa.
- Adipocytes are round to oval with flat nuclei giving rise to “signet ring” appearance
- Thin fibrous capsule seen.
- Lipomas can be classified as classical lipoma and variants.
- Classical lupoma and fibrolipoma-most common
- Intramuscular and spindle cell variant- second most common.
- It contains minute,numerous endothelial lined capillaries.
- The endolial cell lining is single layered.
- Endothelial cells are flat,elongated or plump.
- Endothelial cells form aggregates or rosette around capillaries.
- It contains large dilated endothelial lined sinuses.
- These sinuses contain erythrocytes.
- Flattened endothelial cells and single layered.
- Fibrous conn tissue stroma
- Focal areas of haemorrhage and hemosiderin seen.
- It contains large dilated lymphatics with flat single layered endothelial cells.
- These lymphatics contain lymph.
- The lymphatics replace the connective tissue papillae.
- Cavernous type mostly seen.
- It contains wavy, elongated cels with dark staining nuclei in a collagenous stroma.
- Appears as “shredded carrot” like appearance.
- Cells arranged in fascicles or stripriform pattern.
- Connective tissue shows myxomatous area.
- Tumor derived from shwann cells.
- Two types of arrangement seen.
- Antoni type A- made of cells with elongated or spindle shaped nucleus which are arranged parallel with their intacellular fibres arranged parallel between the rows of nuclei to form characteristic palisading pattern.
- The cells are around eosinophilic acellular area called Verocay bodies.
- Antoni type B- disorganized arrangement of cells and fibres. No palisading pattern.
- Maybe compact or cancellous.
- Compact osteoma made up of dense cortical bone with lamellar pattern.
- Both circumferential and interstitial lamellae seen arranged around a central haversian system.
- Osteocytes seen in lacunae.
- Cancellous osteoma made up of trabecular bone with osteocytes,osteoclasts and osteoblasts.
REFERENCES- Shafer’s textbook of oral pathology 9th edition