FIBROMA

• 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.

LIPOMA

• 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.

CAPILLARY HEMANGIOMA

• 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.

CAVERNOUS HEMANGIOMA

• 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.

LYMPHANGIOMA

• 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.

NEUROFIBROMA

• 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.

NEURILEMMOMA(SHWANNOMA)

• 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.

OSTEOMA

• 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