Pathologic findings:
Consists of four irregular fragments of soft brownish tissues measuring
2.0 cm in dimension. Submitted entirely in two blocks.
| Figure 1 Low power | Figure 2 Low power | Figure 3 Medium power |
| Figure 4 Medium power | Figure 5 High power | Figure 6 High power |
Sections show several mildly enlarged lymph node which are partially destroyed by multiple, well circumscribed collections of activated lymphoid cells accompanied by apoptosis. The pattern is similar to that of Kikuchi's lymphadenitis. The lymphoid cells have large vesicular nuclei with one to multiple prominent nucleoli. These are associated with some histiocytes. No granulocyte could be seen. The residual lymph node parenchyma contains some reactive germinal centres and sheets of matured lymphoid cells interspersed by scattered histiocytes. The features are not suggestive of a lymphoma.
Pathologic Diagnosis:
Left cervical lymph nodes - Histiocytic necrotizing lymphadenitis (Kikuchi's disease). This is a self limiting disease probably of viral aetiology.
Pathologist Comments:
This form of necrotizing lymphadenitis was first described independently in 1972 by Kikuchi and Fujumoto and is prevalent in the East Asia region. Synonyms include: Kikuchi disease, Kikuchi-Fujimoto disease (KFD), histiocytic necrotizing lymphadenitis (HNL) without granulocytic infiltration. It had subsequently been reported from many other places. It is now believed to be due to an exaggerated T-cell response to external antigens, probably the result of viral infection. Recent studies suggest the possibility of human herpesvirus-6 or EBV.
The clinical and pathological features can mimic those of a lymphoma.
It occurs most often in young women (F:M=4:1) and usually involved unilateral
cervical lymph nodes which may be tender. There may be other symptoms such
as fever, sorethroat, skin rash. Laboratory findings include leukopenia
with mild lymphocytosis, neutropenia, presence of peripheral atypical
lymphocytes, and elevated ESR.
The typical histological changes consist of discreet areas of cortical necrosis accompanied by abundant nuclear dusts. These areas are surrounded by lymphohistiocytic infiltrates, immunoblasts and large atypical cells. Neutrophil is absent and few plasma cells are present. Immunohistochemical studies indicate that the lesions are composed primarily of CD15+ histiocytes, CD4+ T cells (in early stages), and CD8+ T cells (in late stages) with relatively few B cells and NK cells. The changes may evolve in three phases: an initial lymphoproliferative phase, a slowly evolving necrotic phase and a final resolving xanthomatous phase.
Distinguishing from lymphoma: incomplete architectural effacement, patent sinuses, mottled appearance of intervening areas, numerous histiocytes, abundant nuclear dusts.
Histology may also simulate SLE. The distinction between SLE and KFD is important since they have differing treatments and prognosis; however they are sometimes indistinguishable. The presence of more numerous plasma cells, hematoxyphilic bodies, deposition of DNA on vessel walls and neutrophilic infiltration favor SLE lymphadenitis. Extensive acellular coagulative necrosis with nuclear dust also suggests SLE. Whenever a diagnosis of KFD is made it may be prudent to rule out the possibility of SLE.
Treatment is symptomatic. Most cases resolve spontaneously in one to three months. One patient died of myocardial disease.
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