Pilomatrixoma Presenting as a Rapidly Expanding Mass of the Infant Nasion

Abstract

Objective: Pilomatrixomas are benign neoplasms originating from the cells of hair follicles. They typically present as a slowly enlarging, solitary mass on hair-bearing areas of the head and neck. While a common childhood lesion, pilomatrixomas are unusual in infancy. Our objective is to present an atypical pilomatrixoma located on the midline nasion of an 11-month-old as such a lesion and its management has not been previously described. Methods: Despite preoperative diagnostic imaging, including computed tomography and magnetic resonance imaging, the diagnosis was not made until examination by pathology after complete surgical excision. We also completed a thorough review of the literature pertaining to pilomatrixomas, which is presented in a concise fashion. Results: Our patient's clinical presentation did not correlate with traditional descriptions in the literature, skewing preoperative diagnosis. However, surgical management was ultimately appropriate and effective. To date, the patient has not demonstrated evidence of recurrence. Conclusion: We believe that this is the first such reported presentation of a pilomatrixoma. Given its incidence, we encourage readers to consider this diagnosis when evaluating similar pediatric skin lesions of the head and neck. Complete surgical excision is the definitive treatment.

Keywords: hair diseases; infant; midline mass; pilomatrixoma; skin neoplasms.

Figure 1

Preoperative lesion progression: progression of midline nasion lesion over 3 months as captured by the patient's mother/guardian. She was 11 months of age at the time of presentation when the last image in the sequence was taken.

Figure 2

Diagnostic imaging: computed tomography of the head with contrast in the axial plane with arrows depicting the lesion in the (A) bone window and (B) brain window. Similarly, postcontrast magnetic resonance imaging of the head in the (C) axial plane, T1 and (D) sagittal plane, magnetization-prepared rapid gradient-echo (MP-RAGE).

Figure 3

Pathology: Low- (A) and high-power (B) photomicrographs of pilomatrixoma showing solid sheets of basaloid cells with bland, round nuclei encircling islands of “ghost cells” with abundant eosinophilic cytoplasm lacking nuclei (hematoxylin and eosin stain, ×100 and ×200, respectively).