Journal of the Bahrain Medical Society
Year 2023, Volume 35, Issue 1, Pages 68-74
https://doi.org/10.26715/jbms.35_1_9Hazem Muhammed Almasarei1 , Darine Helmy Amin Saad2, Suad Muhammad Abu Tahoun3, Sufyan Sameer Sami Alsbahi4, Nandan Maruti Shanbhag5
1Diagnostic & Interventional Radiologist, Canadian Specialist Hospital, Abu Hail Road, Behind Ministry of Environment and Water, P.O.Box: 15881, Dubai, UAE
2Researcher Radiologist, Anthropology Biology Department, National Research Center, Cairo, Egypt.
3Radiology, Dubai, UAE
4Radiology, Amman, Jordan
5Radiation Oncologist, UAE; Email:onco@drnandan.com
*Corresponding author:
Dr. Nandan Maruti Shanbhag, Radiation Oncologist, UAE; Email:onco@drnandan.com
Received date: June 15, 2022; Accepted date: November 28, 2022; Published date: March 31, 2023
For tables and figures, please refer to PDF.
Epithelioid sarcoma of the scalp as a primary site of origin is a rare occurrence a and has a broad differential diagnosis. The radiological features for each of the differential diagnoses are similar but sometimes can be very unique. The present case study provides relevance and significance in considering the possibility of primary epithelioid sarcoma while examining benign lumps with no skin ulceration or pain. The case report focuses on imaging features of epithelioid sarcoma while employing to describe the lesion using multimodality imaging in addition to Computer Tomography, early intervention in the form of complete excision of these tumours through surgery and primary repair when required. Adequate adjuvant treatment is needed following the excision, with the goal of preventing recurrences.
Keywords: Epithelioid Sarcoma, Skull imaging, Osteomyelitis.
Epithelioid sarcoma (ES) of the scalp as a primary site of origin is a rare occurrence and hence possess a challenge in early diagnosis and timely intervention. Only 12 cases of primary epithelioid sarcoma (PES) originating from the scalp have been reported to date, including the present study.1-10 In addition, there is no recommended treatment modality specific for PES of the scalp, the reason being that there have been very few cases and limited study is available on the role of chemotherapy.11 Thus, even in the recent time, wide surgical resection and adjuvant radiotherapy remain the mainstay of treatment.12-16
The present study depicts a case of a 17-years old female clinically presented with a history of scalp lump, mainly in the right frontal region, which interfered with her during praying. Over a period of six months, the subject noticed incidentally a small, slowly growing, painless bulge under the scalp. A neurological examination did not reveal any deficits apart from mild neurological symptoms. Still, a physical examination found a right frontal large firm, painless palpable lump, which had no mobility over the underlying bone and the skin covering the lesion could not be retracted.
Computed Tomography (CT) scan before surgery showed an expansile lytic and destructive bony lesion of the right frontal bone (involving both tables of the skull vault) associated with the large hypo dense intradiploic soft tissue mass lesion with slightly extra-axial extension and minimal indenting the right frontal lobe. It showed a wide transition zone, periosteal reaction and soft tissue component (Figures 1A, 1B).
Bone windows in the CT scan show irregular destruction and erosion of the calvarium’s inner and outer table (Figures 2A-2C). A 3D reconstruction of the skull bone revealed the irregular destruction (Figure 3).The differential diagnosis of the epithelioid sarcomas are very broad (Table 1) and the radiological features for each of the differential are similar but sometimes can be very unique (Figures 4A-4K).
The tumour was resected within the normal bone followed by the excision of the markedly thickened dura. A duroplasty with galeal flap and a reconstruction of the skull bone with a titanium mesh was performed.
Results indicated that it closely resembled an epidermoid cyst, however, histopathological diagnosis of epithelioid sarcoma was established. The tumour cells were diffusely and strongly positive for cytokeratin (CK) AE1/AE3 and negative for epithelial membrane antigen (EMA), P63, S100, CD34, Transducin-like enhancer protein-1 (TLE-1), smooth muscle actin (SMA) and myogenin. BAF47 (INI-1) immunostain was retained in tumour cell nuclei.
External beam radiation therapy (EBRT) and chemotherapy were advised as adjuvant treatment, but the patient and the family refused any further treatment. The patient eventually received adjuvant external beam radiation two weeks later. The patient did not have any adverse event during or immediately following the treatment.
After the intervention, the patient’s neurological status remained stable with intact motor strength and sensation. Long term follow-up was advised to further assess the post-treatment status. A post excision CT of the right frontal skull tumour showed no measurable residual disease and no extra/subdural collections or pneumocephalus with the intact titanium mesh (Figure 5A-5C).A bone scan done after the excision showed a sizable photopenic area within the right side of the frontal bone, which correlated with tumour resection (postsurgical changes). There was no evidence of osteoblastic metastases.
The skull is one of the common sites of metastasis (22%) after lungs (51%) and the regional lymph nodes (34%). ES has a predilection for the male gender and the male to female ratio is 1.2:1. However, among the cases reported for PES of the scalp, including the present study, the ratio was found to be 1.4:1.1-10 The age range at the time of diagnosisis also wide and varies from 1 to 80 years.1 Most of the reported cases of PES are focused on histopathological morphology of epithelioid tumour cells and in this report, the focus is towards the radiological features to reiterate the importance of considering PES as a probable diagnosis from a list of differentials that present with an unknown calvarial lesion.
The most recent case report of PES is similar to this report in that it has focused on imaging features while it employed to describe the lesions using multimodality imaging in addition to CT modality. Compared to the case presented by Zhang et al.1 ,, in which the calvarium had no erosion and the dura was intact, this report illustrates a case where both the tables of the vault showed erosion, with a wide zone of transition, periosteal reaction and thickening of the dura and the soft tissue component. While the case reported by Zhang et al.1 was a fast-growing tumour that grew within a month and became fungating and painful while this case reports a slowly growing tumour over a period of six months with no pain involved.1
Despite the rarity of the tumour, PES is considered as a possibility because on CT scan, it appeared as a well-circumscribed extracerebral hypodense area surrounded by a hyperdense rim with erosion of both tables of the vault. As an unknown calvarial lesion, it is differentiated against 11 types of lesions, namely, eosinophilic granuloma/ histiocytosis, epidermoid/ dermoid cyst, fibrous dysplasia, hemangioma, hemangiopericytoma, giant cell tumour, osteomyelitis, calvarial tuberculosis, brown tumour, metastases, and normal variant.17-20
Eight of the reported cases, including the case reported in this study, were local at the time of diagnosis while two had metastasised to the lymph nodes and one was a recurrence.2-10 Unlike two other cases which had hemorrhage and three cases that had ulcers, the case reported in this study had neither and it was painless at the time of diagnosis.2,5,7,8
The aggressive nature of ES warrants radical tumour resection and lymphadenectomy (in case of lymph node involvemen)t and is often used in combination with radiation therapy (perioperative or postoperative) despite limited data available to support its usage and further research in the field is required.11
After the successful diagnosis of PES of the scalp (within six months of its appearance), the next challenge was surgical intervention and repair of the deformed skull. Upon diagnosis, ES must undergo maximal safe total excision followed by adjuvant radiotherapy to reduce the risk of local recurrence.14-16 Adjuvant radiation therapy is effective in local control but has no effect on overall survival.
The present case report demonstrates the possibility of reconstruction following complete excision of the scalp tumour. A duroplasty with a galeal flap was performed and the skull bone reconstruction was successfully done with a titanium mesh. The patient’s neurologic functioning remained stable and the motor strength and sensation were intact after the surgery. The surgery was followed by EBRT and another dose was planned for two weeks later. There is a mixed pattern of treatment employed in the other eleven cases of PES, wherein, some had sufficed to radical tumour resection, while others combined it with radiation therapy.1-10
The study evidently provides relevance and significance of considering the possibility of primary ES while examining benign lumps with no skin ulceration or pain. The CT scan of all such cases must be examined and differentiated while keeping in mind the chance of ES of the skull to ensure early detection and correct diagnosis. In addition, the early and aggressive intervention of complete tumour resection, radiotherapy, and repair of the damaged bone may contribute to maintain the stability of the patient’s neurological function.
As PES of the scalp is quite rare, additional information about cell morphology could add valuable information to assist in distinguishing ES from other tumours. The study does not include histological features. Moreover, MRI was not employed as an additional modality besides CT scan to strengthen the diagnosis in the context of radiological imaging. The above mentioned aspects can be some of the limitations of this case report. The study recommends early intervention in the form of complete excision of these tumours through surgery and primary repair when required. Adequate adjuvant treatment is needed following the excision, with the goal of preventing recurrences.