vulvar trichogenic tumor
Tuesday 17 March 2009
Trichogenic tumors are very rare in genital skin and often cause diagnostic problems because they are mitotically active and they share some histologic features with basal cell carcinomas (BCCs).
Superficial plaque-like trichogenic tumors feature basal keratinocyte proliferations with peripheral nuclear palisading but no clefting at the epithelial-stromal interface.
Nodular trichogenic tumors consiste of solid lobules of squamous cells and anastomosing cords and reticulations of follicular germinative cells with mitoses and apoptosis.
Large pink cells with trichohyaline granules and melanocytes resembling the inner hair sheath, and clear cells resembling the outer root sheath are common.
Most cysts are keratinized, but some fluid-filled cysts showed apocrine and sebaceous differentiation.
The well-defined mesenchymal component of trichogenic tumors is pale and mucinous, and contain fibrocytes and fibrillary collagen bundles.
All BCCs show surface ulcerations and clefting at the stromal-epithelial interface. BCCs show no trichogenic differentiation and lack an organized mesenchymal tumor component.
The tumor stroma of BCCs is paucicellular, mucinous, or granulation tissue-like with an inflammatory infiltrate.