Kikuchi-Fujimoto lymphadenitis imitating metastatic melanoma on positron emission tomography: a case report.
BACKGROUND
Accurate staging is critical for decision-making for the treatment of malignant conditions. Fluoro-deoxy-glucose positron emission tomography-computed tomography (FDG PET-CT) is a highly sensitive imaging modality for the assessment of distant metastases; however false positive results are possible due to its lower specificity with detection of other hypermetabolic pathologies.


METHODS
A patient with high-risk thigh melanoma was staged with FDG PET-CT. Four ipsilateral inguinal nodes (three superficial, one deep) demonstrated intense hypermetabolic activity. Metastatic melanoma was confirmed in the largest superficial inguinal node with ultrasound-guided fine needle aspiration. Histopathology demonstrated metastatic melanoma in one superficial node and histiocytic necrotizing lymphadenitis, also known as Kikuchi-Fujimoto disease in five deep inguinal nodes.


CONCLUSIONS
This case illustrates a false positive FDG PET-CT due to coincidental, synchronous melanoma and Kikuchi-Fujimoto disease in the same draining lymph node basin.
Queen's University School of Medicine, Kingston, Ontario, Canada.|Department of Surgical Oncology, Tom Baker Cancer Centre, University of Calgary, Calgary, Canada.
Peter
P
Urbanellis
Department of Surgical Oncology, Tom Baker Cancer Centre, University of Calgary, Calgary, Canada.
Laura
L
Chin-Lenn
Department of Pathology, Divisions of Anatomical Pathology and Cytopathology, and Hematopathology and Transfusion Medicine, University of Calgary, Calgary, Canada.
Carolin J
CJ
Teman
Department of Surgical Oncology, Tom Baker Cancer Centre, University of Calgary, Calgary, Canada. Greg.Mckinnon@albertahealthservices.ca.
J Gregory
JG
McKinnon
D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D020042:Histiocytic Necrotizing Lymphadenitis / Q000175:diagnosis*; D006801:Humans; D008545:Melanoma / Q000175:diagnosis*; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18