BACKGROUND: Kikuchi-Fujimoto disease (KFD) or necrotizing histiocytic lymphadenitis, was described separately by both Kikuchi and Fujimoto in Japan in the early 1970\'s. Despite its rarity in the pediatric population, it is an important differential in persistent lymphadenopathy. Familial cases of KFD in the literature are rare. Here we describe the first reported case of KFD in non-identical twin sisters.
METHODS: Twin 1 presented with a 3-week history of worsening right-sided cervical lymphadenopathy, daily fevers, significant lethargy, weight loss and arthralgia of her knees and ankles at the age of 12 years in 2015. She had had an unremarkable medical history. A biopsy of her lymph nodes showed histiocytic necrosis consistent with KFD. Twin 2 presented with a three-week history of lethargy, fatigue, weight loss and left-sided posterior cervical chain lymphadenopathy at 16 years of age in 2018. She had a history of frequently relapsing nephrotic syndrome and celiac disease. A biopsy of her lymph nodes was undertaken and showed histiocytic necrosis consistent with KFD.
CONCLUSIONS: KFD is a rare but self-limiting pathological process of necrotizing histiocytic lymphadenitis. Although further research is needed, there is an increasing amount of evidence which suggests a multifactorial pathological basis of disease. The two cases we document here are the first reported cases of familial KFD in dizygotic HLA-identical twins which reinforces the likely HLA-linkage in the etiology of KFD.

Benign Fibrous Histiocytoma (BFH) is a well recognised tumour of the soft tissue, developing entirely within the subcutaneous tissue, the deep soft tissues or in the parenchymal organs. However, BFH of bones is poorly defined. It has been rarely reported in the bones with femur, tibia and pelvic bone being the most commonly affected bones. Involvement of the jawbones is rare. Their clinical and radiographic features often simulate the common odontogenic and non-odontogenic lesions of the jaws. Hence, it is imperative for a dentist to have proper knowledge of various conditions affecting the jaws. Here we report a case of BFH which presented as an indolent swelling of the right mandibular posterior region for 15 years. The case emphasizes the need for considering BFH in the differential diagnosis of swellings of the jaws.