Reactive lesions Traumatic Neuroma Definition • A reactive/reparative process characterized by proliferation of axons, Schwann cells, and perineurial fibroblasts in a disorganized pattern in the background of collagenous stroma (scar)…

Benign tumors including reactive vascular proliferations and ectasias Intravascular Papillary Endothelial Hyperplasia (Masson tumor) Definition • A nonneoplastic, reactive, endothelial proliferation representing an organizing thrombus, characterized by formation of arborizing…

Benign tumors Superficial Angiomyxoma Definition • An uncommon distinct type of myxoma characterized by the presence of thin-walled blood vessels • This is likely to represent the same entity as…

Benign tumors Glomus Tumor Definition • A benign tumor composed of modified smooth muscle cells (e.g., glomus cells) • Subclassified into three groups based on the proportions of glomus cells,…

Benign tumors and reactive proliferations Osteoma Cutis Definition • Osteoma cutis represents a reactive, metaplastic, lamellar bone formation in the dermis and/or subcutis • Primary and secondary forms of osteoma…

Benign tumors and reactive conditions Lipoma Definition • A benign dermal or subcutaneous mesenchymal tumor composed of mature adult-type adipose tissue Clinical features Epidemiology • The most commonly encountered mesenchymal…

Benign tumors Fibrous Papule Definition • A benign proliferation in the superficial dermis, composed of fibroblasts, blood vessels, and sparse inflammatory cell infiltrate in the background of a sclerotic dermal…

Benign tumors Rhabdomyomatous Mesenchymal Hamartoma Definition • A rare dermal or subcutaneous benign lesion composed of disordered mature elements, including skeletal muscle, adipose tissue, nerve bundles, blood vessels, adnexal tissue,…