Collision of Basal Cell Carcinoma with Apocrine-Sebaceous-Follicular Unit Neoplasms

Area of Science:

• Dermatopathology
• Oncology
• Dermatology

Background:

• Tumor collision is a rare dermatological event, with an incidence of 0.0017%.
• Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) commonly collide with apocrine-sebaceous-follicular unit (ASFu) neoplasms.
• Previous collisions are often considered incidental findings.

Purpose of the Study:

• To compare the collision rates and characteristics of BCC/ASFu neoplasms versus SCC/ASFu neoplasms.
• To identify novel collision types between BCC and ASFu neoplasms.
• To explore potential predisposing factors for tumor collisions.

Main Methods:

• A retrospective study analyzed biopsy files from Dr. José Molina Orosa Hospital (2005-2017).
• Cases involving collisions between BCCs or SCCs and ASFu tumors (including cysts) were identified.
• Data on patient demographics, immunosuppression status, and tumor location were collected.

Main Results:

• Twelve BCC/ASFu neoplasm collisions were identified; no SCC/ASFu collisions were found.
• Common ASFu neoplasms included hidrocystomas, infundibular cysts, and steatocystomas.
• Most ASFu neoplasms occurred beneath the BCC, and a quarter of patients were immunosuppressed.

Conclusions:

• This study reports three new collision types: BCC with infundibular cysts, steatocystomas, and spiradenoma.
• Immunosuppression may be a predisposing factor for BCC/ASFu neoplasm collisions.
• Further research is needed to understand the mechanisms behind these rare tumor collisions.