Malignant Abrikossoff's Tumour of the Tonsil - A Case Report of a Rare Entity.

RATIONALE: This study aimed to report an uncommon site of origin of a rare head-and-neck cancer, namely malignant granular cell tumour.

PATIENT CONCERNS: An 89-year-old female patient complained of persistent pharyngodynia and odynophagia for two months.

DIAGNOSIS: Upon clinical examination, the right palatine tonsil was larger and palpably firmer than the contralateral. An incisional biopsy of the lesion was performed under local anaesthesia revealing malignant granular cell tumour. A contrast-enhanced computed tomography (CECT) scan of the head and neck and an 18F-fluoro-2-deoxy-D-glucose positron emission tomography (PET) scan confirmed the presence of a pathologic appearance of the right palatine tonsil without nodal or distant metastasis.

TREATMENT: Following a multidisciplinary consultation and the patient's informed permission, a right tonsillectomy extended to the constrictor muscle fibres of the upper pharynx was performed.

OUTCOMES: The tumour was staged as pT2 R0 cN0 M0, according to the AJCC 8th edition for soft-tissue tumours of the head and neck. Due to the early stage and the radicality of surgery, no further adjuvant treatments were provided. The patient is currently followed up with no evidence of disease one year post-operatively.

TAKE-AWAY LESSONS: Granular cell tumours are rare mesenchymal tumours, firstly described by the pathologist Abrikossoff in 1926. This type of tumour constitutes approximately 0.5% of all soft-tissue tumours, and can affect any part of the body, with the head and neck being the most frequently involved site. The tonsil is an extremely rare localisation of this cancer. The differential diagnosis of unilateral tonsillar enlargement should also include this histological entity.