Case Number : Case 4151 - 19 December 2022 Posted By: Dr. Mona Abdel-Halim

Proliferation of squamous epithelium with nuclear atypia and mitoses, trichilemmal keratinization, and history of recurrence are suggestive of malignant proliferating trichilemmal cyst

Agree, proliferating pilar tumor, probably malignant.

Agree. Proliferating trichilemmal cyst

Agree..Proliferating trichilemmal cyst..

PTC with some but not many aggressive findings. 

Malignant proliferating pilar tumour due to the cytologic atypia and mitoses

Subjective but I agree with the first entry, malignant proliferating tricholemmal cyst.

Yes this was suspicious of malignant proliferating pilar tumor due to the focal cytological atypia and mitoses but no definite invasive or infiltrative areas were detected in this incisional specimen. A recommendation for complete excision was made. 

p16, p53, Ki67 should be helpful to confirm carcinoma in situ in pilar cyst.