Pilomatricoma is a benign skintumor derived from the hair matrix.[2][3] These neoplasms are relatively uncommon and typically occur on the scalp, face, and upper extremities. Clinically, pilomatricomas present as a subcutaneous noduleorcyst with unremarkable overlying epidermis that can range in size from 0.5 to 3.0 cm, but the largest reported case was 24 cm.[4]
Hybrid cysts that are composed of epidermal inclusion cysts and pilomatricoma-like changes have been repeatedly observed in Gardner syndrome.[7][8][9][10] This association has prognostic import, since cutaneous findings in children with Gardner syndrome generally precede colonic polyposis.[citation needed]
Histologic features
[edit]Micrograph of a pilomatricoma showing the characteristic "ghost" cells (anucleate squamous cells), benign viable squamous cells and multi-nucleated giant cells. H&E stain.
The characteristic components of a pilomatricoma include a stroma of fibrovascular connective tissue
surrounding irregularly shaped, lobulated islands containing basaloid cells (being darkly stained, round or elongated, with indistinct cell borders and minimal cytoplasm, with nuclei being round to ovoid, deeply basophilic and generally prominent nucleoli), which abruptly or gradually transitions into ghost cells (having abundant, pale, eosinophilic cytoplasm, well defined cell borders and a central clear area, but only faint traces of nuclear material), which in turn may transition into keratinaceous to amorphous necrosis.[11]
Pilomatricoma is associated with high levels of beta-catenin caused by either a mutation in the APC gene or a stabilizing mutation in the beta-catenin gene, CTNNB1. A high level of beta-catenin increases cell proliferation, inhibits cell death, and ultimately leads to neoplastic growth.[6]
^Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN978-1-4160-2999-1.[page needed]
^James, William Daniel; Berger, Timothy G.; Elston, Dirk M., eds. (2006). Andrews' Diseases of the Skin: Clinical Dermatology. Saunders Elsevier. p. 670. ISBN978-0-8089-2351-0.
^Levy, Jaime; Ilsar, Michael; Deckel, Yael; Maly, Alexander; Anteby, Irene; Pe'er, Jacob (2008). "Eyelid Pilomatrixoma: A Description of 16 cases and a Review of the Literature". Survey of Ophthalmology. 53 (5): 526–35. doi:10.1016/j.survophthal.2008.06.007. PMID18929763.
^Cooper, Philip H.; Fechner, Robert E. (1983). "Pilomatricoma-like changes in the epidermal cysts of Gardner's syndrome". Journal of the American Academy of Dermatology. 8 (5): 639–644. doi:10.1016/S0190-9622(83)70071-X. PMID6863619.
^Narisawa, Yutaka; Kohda, Hiromu (1989). "An Unusual Hybrid Cyst in Gardner's Syndrome with Partial Differentiation toward the Inner Root Sheath". The Journal of Dermatology. 16 (6): 492–495. doi:10.1111/j.1346-8138.1989.tb01591.x. PMID2628457. S2CID11344468.
^Rütten, A.; Wenzel, P.; Goos, M. (1990). "Gardner-Syndrom mit pilomatrixomartigen Haarfollikelzysten" [Gardner syndrome with pilomatrixoma-like hair follicle cysts]. Der Hautarzt; Zeitschrift für Dermatologie, Venerologie, und Verwandte Gebiete (in German). 41 (6): 326–328. PMID2380070. INIST19291018.
