Kikuchi Disease: Differentiation from Tuberculous Lymphadenitis Based on Patterns of Nodal Necrosis on CT

KD in a 13-year-old boy. Transverse CT image shows a lymph node (arrow) containing multiple necrotic foci in the peripheral portion of the node. The necrotic foci have indistinct margins, and the extent of nodal necrosis accounts for approximately 30%–70% (moderate degree) of the lymph node. The CTN and CTN/M were calculated as 65 HU and 0.9, respectively.

KD in a 31-year-old woman. Transverse CT scan shows 2 lymph nodes with necrotic foci. The larger one (arrow) has a single necrotic focus with a relatively indistinct margin, and the extent accounts for >70% (severe degree) of the lymph node. Perinodal infiltration is seen (arrowhead). The CTN and CTN/M were 43 HU and 0.7, respectively.

TL in a 38-year-old woman. Transverse CT scan demonstrates a necrotic lymph node. The lymph node (arrow) has a single necrotic focus with a well-defined margin, and the extent of nodal necrosis accounts for >70% (severe degree) of the lymph node. The CTN and CTN/M were 29 HU and 0.4, respectively.

TL in a 35-year-old woman. Transverse image shows a lymph node (arrow) having multiple necrotic foci with relatively well-defined margins and a moderate extent of nodal necrosis. Note calcification (arrowhead) within the node. CTN and CTN/M were 38 HU and 0.6, respectively.

TL in a 37-year-old man. Transverse CT scan shows several lymph nodes with necrotic foci. The larger one (arrow) has multiple necrotic foci (not shown in this figure) with well-defined margins and a severe extent of nodal necrosis. Note the obliteration of perinodal fat around the lymph node (arrowhead). The CTN and CTN/M were 22 HU and 0.4, respectively.

Graph of CTN of TL and KD. The mean CTN of KD (70.3 ± 18.01) is significantly higher than that of TL (37.4 ± 20.00). When 44.5 was used as the cutoff value for the CTN, a sensitivity of 89.5% and a specificity of 86.0% were achieved for differentiating KD from TL.