Frequency and features of malignant tumors clinically mimicking cutaneous cysts: A retrospective chart review.

BACKGROUND: Many cutaneous lesions are clinically suspected as "cyst"; however, following histopathological examination, are found to be more significant lesions. Here, we examine the frequency and features of malignancies with cutaneous cysts in the clinical differential.

METHODS: A retrospective study of surgical pathology specimens at the James A. Haley Veterans' Hospital from January 2018 to December 2022 was conducted. Cutaneous specimens containing the clinical diagnosis of "cyst" were included. The clinicopathological features were summarized.

RESULTS: Premalignant or malignant neoplasms accounted for 4.5% of all specimens submitted with cysts in the clinical differential. Most cyst-mimicking cancers were basal cell carcinoma (BCC) or squamous cell carcinoma (SCC); however, cancers with poorer prognoses, such as Merkel cell carcinoma and melanoma, also clinically masqueraded as cysts. The BCCs were predominately nodular, and the SCCs were largely well-differentiated and invasive. Many exhibited clinical signs and symptoms compatible with benign cysts, such as central punctum, pain, and rapid growth. Identified risk factors included history of prior non-melanoma skin cancer diagnosis, previous excision, and immunosuppression.

CONCLUSIONS: Many lesions clinically concerning cutaneous cysts were found to be malignancies following histopathological review. Accordingly, following biopsy all cyst-like lesions should be examined microscopically, especially in certain clinical contexts in which the incidence of skin cancer is increased.