Sporadic trichoepithelioma demonstrates deletions at 9q22.3.
BACKGROUND
Trichoepithelioma (TE) is a benign cutaneous tumor that originates from hair follicles and occurs either in multiple or solitary lesions. Multiple TE is transmitted as an autosomal dominant trait, and a region at 9p21 is thought to be involved in the tumorigenesis. Solitary TE occurs more commonly than multiple TE and is not inherited. Histologically, TE tumors contain horn cysts and abortive hair papillae. A basal cell carcinoma appearance in some or all regions of a TE tumor can happen. In sporadic basal cell carcinoma, frequent deletions at 9q22.3 (Drosophila patched gene) have occurred. The objective of this study is to test whether loss of heterozygosity (LOH) on either 9p21 or on chromosome 9q22.3 could be detected in archival sporadic TE.


METHODS
We studied 29 randomly selected cases of sporadic TE by microdissection and polymerase chain reaction using paraffin-embedded, formalin-fixed tissue specimens on glass slides. Analysis was performed with the polymorphic markers IFNA and D9S171 (9p21) as well as D9S15, D9S303, D9S287, and D9S252 (9q22.3).


RESULTS
The LOH at 9q22.3 was identified in 14 (48%) of 29 cases with at least 1 marker, while LOH could not be demonstrated using the markers IFNA and D9S171 (9p21).


CONCLUSIONS
The results show that the Drosophila patched gene LOH can be frequently identified in paraffin-embedded sporadic TE after routine processing and indicates a common gatekeeper mechanism for both TE and basal cell carcinoma.
Matt
D
D
Department of Dermatology, University Hospital of Zurich, Switzerland.
Xin
H
H
Vortmeyer
A O
AO
Zhuang
Z
Z
Burg
G
G
Böni
R
R
D002899:Chromosomes, Human, Pair 9; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000737:chemistry; D005260:Female; D005819:Genetic Markers; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D018295:Neoplasms, Basal Cell / Q000235:genetics* / Q000473:pathology; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction; D011897:Random Allocation; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology
D017931:DNA Primers; D004273:DNA, Neoplasm; D005819:Genetic Markers