This 63-year old woman presented with a 1.0-centimeter nodule on her scalp. Cylindroma is a benign adnexal neoplasm that most commonly affects women in the third to fifth decades of life. There is a marked preponderance for this tumor to occur on the head, neck, and scalp. It is usually asymptomatic, grows slowly, and averages 1 centimeter in size. Multiple cylindromas may occur with eccrine spiradenomas and trichoepitheliomas in the autosomal dominant Brooke-Spiegler syndrome (familial cylindromatosis or turban tumor syndrome). Both the sporadic and familial forms of cylindroma have been shown to result from inactivation of the CYLD tumor suppressor gene in chromosome 16q12-q13. The basement membrane-like material within and surrounding the tumor lobules are composed of proteins found normally at the dermal-epidermal junction and are thought to result from defective processing of laminin 5 by the tumor cells. The main differential diagnosis of cylindroma is its cousin eccrine spiradenoma. The latter tumor is distinguished from cylindroma by its fewer but larger tumor lobules and by the prominence of dilated vascular spaces within these lobules.
Higher power view reveals the tumor lobules to be composed of two distinct populations of cells: smaller palisaded basaloid cells in the periphery surrounding larger cells with pale cytoplasm and vesicular nuclei. Admixed with the tumor cells are variable amounts of hyaline droplets of similar quality to the basement membrane-like material bordering the lobules.