Clinical history: 51 year old man with a history of multiple previously excised cysts of the scalp.
What is the diagnosis?
Benign adnexal tumor showing features of cylindroma and spiradenoma
These eccrine tumors can be seen together, also in conjunction with trichoepitheliomas. Occasional cases showing characteristics of both cylindroma and spiradenoma suggest the similar derivation of both tumors. These are most often seen as solitary or multiple tumors on the head and neck. Solitary lesions occur sporadically; multiple tumors are observed in an autosomal dominant inherited manner. Brooke-Spiegler syndrome manifests as multiple recurrent eccrine adenomas on the head and neck; because of its distribution and appearance, this syndrome also has the name “turban tumor.”
Brooke-Spiegler syndrome is a familial eccrine adenomatosis was thought to be due to germline mutations in the cylindromatosis (CYLD) gene. However, there is no firm genotype-phenotype correlation in the syndrome; there is a subset of patients with Brooke-Spiegler syndrome or multiple familial trichoepithelioma who do not show a germline CYLD mutation.
These tumors are typically benign. The rate of malignant transformation of spiradenomas is very low. However, metastasis is seen in about 50 % of cases with malignant transformation.
Grossly, these lesions appear as pink-red smooth dome shaped nodules. They are painful and slow-growing. They may follow a linear or Blaschkoid distribution (following the path of Blaschko’s lines in the skin).
Microscopically, spiradenomas are sharply circumscribed and lobular. They are very cellular; however the cells have scan cytoplasm. They are highly vascular. There may be a variable lymphocytic infiltrate.
Cylindromas form compact nests of basaloid cells that fit together in a “jigsaw puzzle” pattern. The “pieces” of the jigsaw puzzle are surrounded by thick basement membrane; this material may expand to form the appearance of cyst-like spaces.