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Frequent activating HRAS mutations in trichilemmoma
J-H Tsai1, W-C Huang, J-Y Jhuang
1Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Taiwan.
The British Journal of Dermatology
|June 4, 2014
Summary
Most trichilemmomas, benign skin tumors, are driven by HRAS gene mutations. These HRAS mutations, particularly c.37G>C, are common in both naevus sebaceus-related and sporadic cases, indicating they are true neoplasms.
Area of Science:
- Dermatopathology
- Oncology
- Molecular Biology
Background:
- Trichilemmoma is a benign tumor of follicular epithelium.
- Its association with Cowden syndrome and naevus sebaceus (NS) is known, but sporadic tumor pathogenesis is unclear.
- Recent findings link NS to HRAS or KRAS mutations.
Purpose of the Study:
- To investigate RAS gene mutations in trichilemmomas.
- To compare mutation status in NS-related versus NS-unrelated tumors.
Main Methods:
- Analysis of 12 NS-related and 15 NS-unrelated trichilemmomas.
- PCR and direct sequencing of HRAS, KRAS, and NRAS genes (exons 1-2).
- Analysis of FGFR3 and PIK3CA hotspots in sporadic cases.
Main Results:
- HRAS mutations (c.37G>C and c.182A>G) were found in 20 of 27 trichilemmomas.
- HRAS c.37G>C occurred in 11/12 NS-related and 6/15 sporadic tumors.
- HRAS c.182A>G occurred in 3/15 sporadic tumors, not in NS-related tumors.
Conclusions:
- The high frequency of HRAS mutations suggests trichilemmomas are true neoplasms.
- Specific HRAS mutations are prevalent in both associated and sporadic forms.
- The c.182A>G mutation is specific to sporadic trichilemmomas.
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