Abstract Muir-Torre Syndrome is defined by the coexistence of sebaceous skin tumors and internal malignancies. Mutations in the DNA mismatch repair genes are found in the inherited form of the disease, resulting in the absence of crucial enzymes involved with DNA replication process. This case describes a patient with sebaceous adenoma and colorectal carcinoma, meeting the criteria for Muir-Torre Syndrome. The immunohistochemical analysis of the skin lesion was an important tool to confirm the diagnosis, as it revealed nuclear negativity for MSH2 and MSH6.

Temporal triangular alopecia, also referred as congenital triangular alopecia, is an uncommon dermatosis of unknown etiology. It is characterized by a non-scarring, circumscribed alopecia often located unilaterally in the frontotemporal region. It usually emerges at ages 2-9 years. Alopecia areata is the main differential diagnosis, especially in atypical cases. Dermoscopy is a noninvasive procedure that helps distinguish temporal triangular alopecia from aloepecia areata. Such procedure prevents invasive diagnostic methods as well as ineffective treatments.