Large dermoid cyst of the left hip: radiological approach with histopathology assessment.

To cite: Psaras KKP, Triantos G, Papavassiliou T, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2012007943 DESCRIPTION A 72-years-old woman presented to the emergency department for evaluation of a large soft tissue mass (figure 1). X-ray film and ultrasound soft tissue of the left hip were carried out. On X-ray a large soft tissue mass was discovered (figure 2). The patient was then followed with musculoskeletal ultrasound (Philips HD11 with head transducer L12-3) and revealed a lesion of mix type 7×7.5 cm with internal echogenicity and microcalcifications (figures 3 and 4), and later underwent MRI Philips intera. The protocol included imaging in transverse and coronal level, with sequences T2-weighted, short-tau inversion recovery and gradient echo with fat-suppression before and after intravenous injection of paramagnetic contrast, and discovered an enhancing signal mass with multiple scattered low signal microfoci that correspond in fibrous elements, keratin debris, microcalcifications and patchy peripheral uptake of the lesion (figures 5– 8). When the patient was lead to the operating room for mass excision, the specimen was sent for biopsy and was assessed the diagnosis of a large dermoid cyst. Dermoid cyst is a cystic teratoma that includes mature skin completely with hair follicles and sweat glands, sometimes hair, and often pockets of sebum, blood, fat, bone, nails, teeth, eyes, cartilage and thyroid tissue. Because it contains mature tissue, a dermoid cyst is almost always benign. The rare malignant dermoid cyst develops squamous cell carcinoma in adults; in babies and children it can develop into an endodermal sinus tumour. Additionally, regarding the skin, dermoid cysts could be intracranial, intraspinal or perispinal. The term dermoid cyst can be found in all disciplines; however the common factor is the presence of a solitary or multiple hamartomatous tumour. The tumour is covered by a thick wall which contains sebaceous glands and all skin adnexa. In addition, hairs and large amounts of fatty masses originated from the ectoderm can be found. Dermoid cysts can be discovered as cutaneous cysts on the head, as cysts on the floor of the mouth or elsewhere in the head, within the parotid gland or as cysts in the testes or penis. They can be large. Depending on the location of the lesion, dermoid cysts may contain substances such as nails and dental, cartilage-like and bone-like structures. If limited to the skin or subcutaneous tissue, dermoid cysts are thin-walled tumours that could contain different amounts of fatty contents. Radiography, CT scanning and MRI are promising imaging methods in making the correct differential diagnosis of dermoid cysts. MRI is particularly helpful in diagnosing intracranial or intramedullary dermoid cysts