Margins Matter: Surgical Outcomes in Malignant Proliferating Trichilemmal Tumor of the Scalp

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Background: Malignant proliferating trichilemmal tumor is a rare adnexal malignancy derived from the outer root sheath. It most often affects the scalp and may be mistaken for squamous cell carcinoma because of overlapping clinical and histopathological features. As a result, management is largely informed by small case series and case reports. Methods: We retrospectively reviewed 11 consecutive patients with histopathologically confirmed malignant proliferating trichilemmal tumor managed at two tertiary referral centers between January 2020 and May 2024. Demographic, clinicopathological, operative, immunohistochemical, and follow-up data were analyzed. To place our cohort in context, we also performed a focused narrative review of the recent literature on malignant proliferating trichilemmal tumor and related trichilemmal malignancies. Results: The mean age was 64.1 ± 5.7 years (range, 55–74 years), and 7 patients were female. Mean tumor diameter was 27.5 ± 9.1 mm. Five patients (45.5%) had coexisting trichilemmal cysts. All patients underwent wide local excision with planned 1–2 cm clinical margins; 6 patients (54.5%) required local or free flap reconstruction. p53 showed diffuse nuclear positivity in 10 of 11 tumors (90.9%), and Ki-67 exceeded 20% in 8 of 11 (72.7%). Two patients (18.2%) had compromised deep margins on the index excision specimen and underwent re-excision. No local recurrence, nodal disease, or distant metastasis was identified during a mean follow-up of 16.3 ± 5.4 months. Conclusions: In this cohort, malignant proliferating trichilemmal tumor behaved primarily as a locally aggressive scalp malignancy in which adequate deep clearance was critical to definitive surgical management. Achieving histologically clear margins—particularly at the deep plane—and performing prompt re-excision when margins were compromised were the decisive factors for local control. Misinterpretation as squamous cell carcinoma remains a diagnostic pitfall on limited biopsy material and the reconstructive burden is notable, with more than half of patients requiring complex reconstruction. Mohs micrographic surgery is a reasonable option in selected cases, though the supporting data come largely from trichilemmal carcinoma and should not be applied to malignant proliferating trichilemmal tumor without caution. Careful pathological review and long-term follow-up are necessary for all patients.
Funding Information
  • Ankara Universitesi

This publication has 26 references indexed in Scilit: