A Case of Cutaneous Squamous Cell Carcinoma of the Scalp Infiltrating to the Calvarial Bone and Dura Mater

Dear Editor:

It is generally known that squamous cell carcinoma (SCC) has a good prognosis with less local invasion and distant metastasis¹. Here, we present a rare case of scalp primary SCC infiltrated to underlying calvarial bone and dura mater.

A 60-year-old male visited our clinic presented with ulcer and central nodule on right frontoparietal scalp. About 50 years ago, the patient had a history of burn on scalp. In burn scar, ulceration and recovery repeatedly occurred since 15 years ago. From 3 months ago, ulcer on the burn scar had widened and sometimes pus was secreated.

Physical examination revealed poorly demarcated, solitary, 4.3×3.6 cm sized ulcer and central nodule with crust upon the burn scar (Fig. 1A, B). Skin biopsy revealed well-differentiated SCC and there were no metastases to surrounding lymph nodes on computed tomography imaging.

Fig. 1. (A) A solitary, poorly demarcated, 4.3×3.6 cm sized, erythematous crusted ulcer and central nodule on the right frontoparietal scalp of a 60-year-old male. (B) Close-up view of the lesion. (C) Magnetic resonance T1-weighted transverse image revealed 3.0×2.2 cm peripheral enhancing mass at the right frontoparietal skull with diffuse pachymeningeal enhancement dural invasion (yellow arrow). We received the patient’s consent form about publishing all photographic materials.

Initially, wide excision of SCC was performed. During operation, about 2.5×1.5 cm sized, dumbbell shaped bony defect was founded after soft tissue removal. For the precise evaluation, magnetic resonance imaging (MRI) was performed, and which revealed 3.0×2.2 cm peripheral enhancing mass at the right frontoparietal skull with diffuse pachymeningeal enhancement dural invasion (Fig. 1C). Positron emission tomography–computed tomography (PET-CT) showed no another abnormal finding suggesting malignancy.

Additional wide excision of affected calvarial bone and dura mater was performed in neurosurgery. Defect was reconstructed by using duropalsty and latissimus dorsi muscle flap in plastic surgery. After surgery, adjuvant radiation therapy was done. Removal of SCC and reconstruction was successful without recurrence until 1 year. As a sequelae, the patients complains of mild numbness of his left leg.

SCC develops within scars or chronic skin injuries or Marjolin’s ulcer tend to be more aggressive, have poor prognosis and difficult to treat than SCC of different etiology¹. According to Hahn et al.², 32% of patients with malignant ulceration, at the time of diagnosis are found with a diffuse process. Metastases are rather frequent and are found in more than 32% of patients. We inferred the patient had cicatricial alopecia due to burn scar, actinic damage may be accumulated. In the patient, ultraviolet radiation exposure, burn scar and ulcer induced by trauma may contribute to malignant transformation of the skin.

SCC can produce substantial local destruction along with disfigurement and may involve extensive areas of bone or the orbit rarely³. Jambusaria-Pahlajani et al.⁴ reported only 2% of the cohort have SCC with bone invasion. Compared to relatively well known SCC of temporal bone originated from auditory organ and oral mucosa, the current literature on frontal or parietal bone malignancies is extremely limited by the rarity of these tumors. Patients with high risk of aggressive SCC—SCC derived from burn scar, chronic ulcer or chronic inflammation—need to perform expeditious biopsy, avoid sunlight exposure, be cautious of additional trauma, and be on active surveillance. Also, when patients with high risk of aggressive SCC diagnosed as SCC, doctors need to consider further radiologic examination (e.g. MRI) for evaluation invasion depth and metastasis.