Kikuchi-Fujimoto disease is a self-limited febrile lymphadenitis of unknown etiology, possibly associated with cutaneous lesions. We report a case of Kikuchi-Fujimoto disease presenting with papular lesions limited to the elbows and knees. The skin biopsy specimen showed spongiosis and pseudo-Pautrier abscesses in addition to the typical histopathological findings of Kikuchi-Fujimoto disease. Although necrosis was not observed in the lymph node biopsy specimen, histopathological and immunohistochemical findings were consistent with Kikuchi-Fujimoto disease in the proliferating phase. Kikuchi-Fujimoto disease (KFD) is a self-limited febrile lymphadenitis of unknown etiology, predominantly affecting the cervical lymph nodes of young adults.1 Nodal lesions show paracortical necrosis with non-neutrophilic karyorrhexis, infiltration of CD8+ T cells and myeloperoxidase (MPO)+ histiocytes, and CD123+ plasmacytoid dendritic-cell clusters, although necrosis may be absent depending on the disease phases.1, 2 Cutaneous lesions have been reported in up to 40% of cases.3 The skin manifestations are variable, but often present on the upper body.4-6 We report a case of KFD with papular lesions limited to the elbows and knees. A 20-year-old man presented with a 2-week history of fever. Physical examination revealed non-tender lymphadenopathy of bilateral posterior cervical, axillary, and inguinal lymph nodes and non-pruritic erythematous papules on the elbows and knees (Figure 1A,B). Laboratory tests showed elevated levels of C-reactive protein (3.62 mg/dL) and serum lactate dehydrogenase (318 U/L; reference range, 124–222 U/L) and decreased white blood cell count (1700/μL). Anti-nuclear antibodies were negative. Computed tomography did not detect central lymph node swelling. The skin biopsy specimen showed interface dermatitis, papillary dermal edema, and dermal infiltrate (Figure 1C). In the epidermis, spongiosis and pseudo-Pautrier abscesses were present (Figure 1D). The dermal lymphohistiocytic infiltrate was associated with karyorrhexis in the absence of neutrophils (Figure 1E). Most lymphocytes were positive for CD3 and contained both CD4+ and CD8+ cells, although most of the intraepidermal T cells were CD8+ cells expressing TIA1, perforin, and granzyme B. The dermal infiltrate contained numerous CD68+ (clones KP-1 and PG-M1) histiocytes (Figure 1F) that were comprised of CD163+, MPO+, and CD123+ cells. The lymph node biopsy specimen showed paracortical lymphohistiocytic infiltrate with karyorrhexis in the absence of neutrophils (Figure 1G). CD8+ T cells predominated over CD4+ cells (Figure 1H,I). CD68+, CD163+ histiocytes were abundant, and most of them expressed MPO (Figure 1J,K). Clusters of CD123+ plasmacytoid dendritic cells were present (Figure 1L). Although necrosis was not observed in the lymph node biopsy specimen, the diagnosis of KFD in the proliferative phase was made based on the histopathological and immunohistochemical findings.1, 2, 4-6 Only supportive therapies with an oral non-steroidal anti-inflammatory drug and topical corticosteroid were given. Fever, lymphadenopathy, and cutaneous lesions resolved spontaneously in 5 weeks after the disease onset. Cutaneous lesions of KFD are characterized by superficial and deep dermal lymphohistiocytic infiltrate, non-neutrophilic karyorrhexis, interface dermatitis, and papillary dermal edema.4-6 Although spongiosis was observed in some cases,5, 6 presence of pseudo-Pautrier abscesses has not been reported. The reason why the cutaneous lesions in our case were limited to the elbows and knees is unknown, but their localization and the spongiotic epidermal changes suggest involvement of exogenous stimuli. Differential diagnosis of KFD mainly includes SLE and lymphomas.1 In our case, serum anti-nuclear antibodies were negative, and clinical signs suggestive of SLE other than fever and lymphadenopathy were absent. Histopathological and immunohistochemical findings of skin and lymph node biopsy specimens excluded both SLE and lymphomas. In patients with cutaneous eruptions, fever, and lymphadenopathy, KFD should be considered. Immunohistochemical studies are useful for accurate diagnosis, especially in atypical cases. We thank K. Gunshin for her technical assistance. The authors declare no conflict of interest. Approval of the research protocol: N/A. Informed consent: Written informed consent was obtained from the patient. Registration No. of the study/trial: N/A. Animal studies: N/A. The data that support the findings of this study are available from the corresponding author, K.K., upon reasonable request.
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Aug 24, 2024
Zhaoquan Wu + 2
Open Access