What are the common masses that present in the frontal area and how are they diagnosed and treated?

Common Masses Presenting in the Frontal Area

The most common masses presenting in the frontal area include frontonasal dermoid sinus tracts (DSTs), frontal encephaloceles, frontal meningiomas, and frontal lobe gliomas, with frontonasal DSTs being particularly important to recognize early due to their risk of intracranial infection.

Frontonasal Dermoid Sinus Tracts

Frontonasal DSTs are easily overlooked or misdiagnosed as simple pimples or comedones, yet 10-30% extend intracranially through the foramen cecum at the skull base. 1

• These lesions present as innocuous-appearing midline frontal masses from which sebaceous or creamy fluid can sometimes be expressed 1
• The subcutaneous tract extends to the skull base between the nasal bone and nasal cartilage 1
• Critical diagnostic approach requires both CT and MRI: CT reveals bony defects at the foramen cecum or intracranial calcifications, while MRI detects soft tissue components and intracranial dermoid/epidermoid cysts 1
• Surgical excision is recommended regardless of imaging findings to prevent future complications including meningitis, subdural empyema, or brain abscess 1

Frontal Encephaloceles

Frontal encephaloceles represent focal herniation of meninges with or without brain tissue through a skull defect and are most common among Asian populations (whereas occipital encephaloceles predominate in European/North American populations). 1

• These present as visible midline frontal masses that may be confused with other congenital lesions 1
• Prognosis depends heavily on the amount and type of neural tissue within the sac 1
• Atretic parieto-occipital encephaloceles can be confused with cutis aplasia congenita, appearing as small areas of dysplastic skin surrounded by whorls of distinctly colored hair ("horse collar" sign) 1

Frontal Meningiomas

Frontal convexity meningiomas are among the most common intracranial locations for these tumors, particularly in pediatric patients where up to 90% of meningiomas are supratentorial. 1

• Presenting symptoms include headaches, drowsiness, vomiting from raised intracranial pressure, focal neurological deficits, and seizures (in up to 30% of cases) 1
• MRI is the imaging modality of choice: meningiomas appear isointense or hypointense on T1-weighted images and hyperintense on T2-weighted images with strong uniform contrast enhancement 1
• The characteristic "dural tail sign" is suggestive but not pathognomonic 1
• Frontal bossing or tumor formation on the cranial vault may occur in very young children 1

Frontal Lobe Gliomas

Isolated frontal lobe mass lesions may present with varying manifestations of gait and limb ataxia, in addition to other focal neurological deficits. 1

• Frontal lobe gliomas, particularly glioblastomas, diffusely infiltrate surrounding tissues and frequently cross the midline to involve the contralateral brain 2
• Complete surgical resection is impossible due to infiltrative nature: tumor cells extend well beyond contrast-enhancing portions visible on imaging into the peritumoral edema 2
• Unlike oligodendrogliomas which are often well-demarcated in frontal lobes, glioblastomas lack distinct tumor margins 2

Diagnostic Algorithm

For any frontal mass, the evaluation should prioritize:

1. Detailed history focusing on: age of onset, growth rate, associated symptoms (headaches, seizures, neurological deficits, drainage from the mass), and risk factors for malignancy 1

2. Physical examination specifically assessing: exact location (midline vs lateral), size, consistency, mobility, presence of overlying skin changes, and complete neurological examination 1

3. Imaging sequence:

   • MRI with and without contrast is the primary modality for soft tissue characterization, intracranial extension, and relationship to critical structures 1
   • CT with bone windows to evaluate bony defects, calcifications, and hyperostosis 1

4. Tissue diagnosis: Surgical excision or biopsy is typically required for definitive diagnosis, with pathology guiding further management 1

Critical Pitfalls to Avoid

• Never dismiss a midline frontal lesion as a simple "pimple" without imaging evaluation, as frontonasal DSTs require surgical treatment to prevent life-threatening intracranial infection 1
• Do not rely on imaging alone to exclude intracranial extension of frontonasal DSTs, as intracranial tracts may not always be visible even on MRI 1
• Avoid assuming complete resection is possible for frontal gliomas based on imaging appearance, as infiltration extends beyond visible margins 2