Proliferation of atypical keratinocytes typically confined to basilar 1/3 of epidermis Overlying parakeratosis and basilar budding usually seen • Solar lentigo (lentigo senilis) Elongated, hyperpigmented rete ridges Lacks keratinocyte atypia/pleomorphism • Seborrheic…
Glandular differentiation is often present; not as common as in benign mixed tumor of skin Irregular nests, cords, and sheets of cuboidal or polygonal cells Foci of highly atypical cells…
Lacks thick-walled vessels • Cavernous hemangioma Ectatic, thin-walled vessels • Venous hemangioma • Venous lake Single, dilated, thin-walled vessel • Angioleiomyoma Syncytial proliferation of vascular smooth muscle Low-Power Image of Arteriovenous HemangiomaLow magnification of…
EMH With MegakaryocyteThis is a skin biopsy specimen with extramedullary hematopoiesis (EMH), as evidenced by the large megakaryocyte . EMH With Erythroid CellsThis cutaneous lesion contains small clusters of nucleated…
Granular cell tumor Lymphoma • Reaction pattern in certain inflammatory conditions such as Lichen planus Lupus erythematosus • Reaction pattern overlying certain infections Particularly deep fungal • Reaction pattern overlying tattoos Particularly red…
Hobnail HemangiomaLow-magnification view of a hobnail hemangioma (HH) demonstrates superficial dilated vascular spaces in the papillary dermis with deeper small blood vessels and stromal hemosiderin deposits . Higher Magnification of…
History of breast carcinoma May be indistinguishable histologically and immunohistochemically from apocrine carcinoma • Primary cutaneous adenoid cystic carcinoma Cribriform pattern within islands that are relatively uniform in size/shape and not…
Round to slightly oval nucleus with pink cytoplasm • Grains Raisinoid nuclei with pink cytoplasm • Minimal to no cytologic atypia Top Differential Diagnoses • Darier disease Histologically similar Clinically different – Multiple lesions…
Related to chronic actinic damage • Head and neck • Especially common on lip • Can clinically mimic melanoma • Often multiple • Laser treatment Microscopic • Ectatic vessel in upper dermis • Usually single dilated vessel…
> 50% are painful • Treatment: Simple, conservative excision • Excellent prognosis; very rarely recurs Macroscopic • Usually < 2 cm Microscopic • Sharp circumscription • 3 types described: Solid (most common), venous, and cavernous…
