Thyroglossal duct cysts and dermoid cysts both commonly present as midline neck lumps in children. They are treated as separate entities with different embryological origins. There are isolated reports of thyroid gland tissue in a dermoid cyst, concurrent thyroglossal and dermoid cysts, and cysts with mixed histology. It is not known if these are rare or common.

All children undergoing excision of a congenital midline neck cyst between January 2017 and December 2022 were identified. Histopathology slides were reviewed in detail.

In 53 children, there were 26 thyroglossal duct cysts, 24 dermoids, 1 lymph node and 2 with no diagnostic material identified. Five dermoids (28 per cent) had associated thyroid gland tissue, and 1 (4 per cent) had hybrid histology with keratinising and respiratory epithelium. Infection occurred in 17 per cent of dermoids prior to excision and 8 per cent of dermoids recurred after excision.

Hybrid histology, infection and recurrence are all common in midline neck dermoids. A new theory for their embryological origin is proposed, with the suggestion that some may need more extensive surgery.

Dermoid cysts in the floor of the mouth are relatively uncommon developmental lesions. They are thought to arise in the midline and along the lines of embryonic fusion of the facial processes containing ectodermal tissue.

A 17-year-old female presented with a 3-month history of a growing, progressive swelling in the mouth floor. Clinical examination revealed a rather large symmetrical, soft swelling in the mouth floor, displacing the tongue superiorly. The fast growing nature and size of the lesion raised suspicion of potential compromise to the airway. Surgical excision was therefore performed.

Differential diagnosis of cystic lesions in the floor of the mouth is of paramount importance, as the recommended surgical techniques vary depending on the anatomical position of the lesions. The intraoral approach is preferred for those lesions that do not extend beyond the mylohyoid muscle boundaries; this leads to a satisfactory cosmetic and functional outcome.

There have been few reports of lingual dermoid cysts with a congenital discharging fistula. We report such a case, which mimicked lipoma on computed tomography, and we discuss relevant clinical and radiological features.

We present a case report and a review of the English language literature concerning lingual dermoid cysts either mimicking lipoma or with a congenital discharging sinus.

A 35-year-old man presented with a lingual mass associated with a congenital fistula in the midline of the tongue dorsum, which discharged abnormal secretions. Computed tomography images showed that the lesion was well defined and contained homogeneous fatty tissue giving computed tomography attenuation values of −120 Hounsfield units.

Lingual dermoid cysts may develop with a midline discharging fistula, and may exhibit radiological similarity to lipomas on computed tomography.

Dermoids presenting in early life with a sinus tract along the midline of the nasal dorsum are well described. We present three very unusual variants of this condition.

Case one was a two-year-old child with a pit in the philtrum of the lip. The tract pierced the nasal spine and extended towards the crista galli. Case two was a 15-month-old child with two separate sinus openings on the dorsum, one below and one above a dermoid cyst. Case three was a 17-year-old adolescent with neurological disability. Scanning showed a dermoid cyst deep in the anterior skull base, but the sinus tract had been obliterated by bony overgrowth due to long term use of antiepileptic medication.

Cases one and two were successfully managed by complete excision via an external rhinoplasty approach. Case three, in contrast, was not operated upon due to bony obliteration of the sinus tract.

Surgeons dealing with nasal dermoids must be able to adapt to the variable anatomical and clinical features of these lesions.

Nasal dermoid cysts are congenital lesions which are often diagnosed in infancy or childhood. However, a small number present in adulthood, and some extend intracranially. Traditional treatment for the intracranial portion of these cysts includes frontal craniotomy.

Two intracranial dermoid cysts were resected via a transnasal endoscopic approach, using 70° nasal endoscopy for complete visualisation and intracranial tumour removal. We describe our technique for the procedure itself and for reconstruction of the skull base defect.

The endoscopic transnasal skull base approach is an excellent alternative to a traditional frontal craniotomy, to achieve complete resection of intracranial dermoid cysts.

We report a rare case of parotid dermoid cyst.

A case report of parotid dermoid cyst is presented, as well as a brief review of the literature and a summary of the lesion's salient clinicopathological features.

A 69-year-old man presented with a slow-growing, soft tissue mass of the left parotid gland. Pre-operative evaluation included fine needle aspiration cytology and computed tomography. He subsequently underwent a superficial lobectomy; both the macroscopic and histopathological findings were consistent with a dermoid cyst. Although dermoids within the head and neck are not uncommon, such cysts have only rarely been encountered in the parotid gland.

To our knowledge, there are only four previous case reports of parotid dermoid cyst in the English literature. Although the majority of cases of parotid dermoid cyst are diagnosed retrospectively, our case demonstrates the role of fine needle aspiration cytology and highlights the key cytological features suggestive of this entity.