Rosai Dorfman disease (RDD), also known as sinus histiocytosis with massive Lymphadenopathy (SHML), is a rare benign self-limiting disorder of histiocytic proliferation that commonly involves lymph nodes.[1]. Rosai and Dorfman first described it in 1969. SHML is mainly characterized by massive, painless, bilateral cervical lymph node enlargement, associated with fever, leukocytosis, elevated erythrocyte sedimentation rate, and polyclonal hypergammaglobulinemia.

Other lymph nodes, as well as extranodal sites commonly involved, are eye, ocular adnexa, head and neck region, upper respiratory tract, skin, subcutaneous tissue, skeletal system, central nervous system, gastrointestinal tract, thyroid, genitourinary system, breast, liver, kidney, heart etc. [2]. Most cases occur during the first or second decade of life, but any age group can be affected. RDD has distinct cytological features. Fine needle aspiration cytology plays a significant role in primary diagnosis.

An 18 months old Indian female child presented with slowly enlarging painless bilateral cervical lymph nodes for one year. There was no history of night sweat, loss of appetite or low-grade fever. On clinical examination, the patient had bilaterally enlarged, soft to firm, mobile, non-tender cervical lymph nodes.

Figure:1 shows enlarged lymphadenopathy

The lymph nodes on the left side were two in number, first measuring 1.5x1.5 cm and the other 1.5x1 cm in size, and the lymph node on the right side was 1.5 x 1 cm. The overlying skin was normal.

The histiocytes had fine nuclear chromatin and pale abundant cytoplasm. There was no nuclear atypia or grooving. Caseous necrosis or epithelioid cells were also not seen. AFB stain was negative. Based on this characteristic cytomorphology, a diagnosis of Rosai-Dorfman disease was made.

SHML is a rare self-limiting benign histiocytic proliferative disorder of unknown aetiology. The most likely possibilities being infection by a virus or some other microorganism and the manifestation of a subtle undefined immunologic defect. Although Human Herpesvirus 6, Epstein Barr virus and polyomavirus have been suggested, but not been proven. It has been recommended that stimulation of monocytes/macrophages via macrophage colony-stimulating factor(M-CSF) leading to immune suppressive macrophages may be the primary pathogenetic mechanism. Any age group can be affected, including paediatric and elderly patients [1,3]. Involvement of axillary, paraaortic, mediastinal and inguinal lymph nodes have been reported in RDD [3]. In our patient multiple enlarged non-necrotic cervicals, axillary, paratracheal, perivascular, periportal and mesenteric lymph nodes were present. There was no extranodal involvement in our patient.

The other features are fever, leucocytosis, elevated ESR and polyclonal gammaglobulinemia. In the present case, the patient had multiple enlarged lymph nodes with leucocytosis and elevated ESR. Clinically patient was suspected of tuberculosis or lymphoma, and the possibility of RDD was not suspected until FNAC was performed. The specific cytomorphological features are diagnostic for RDD.FNAC shows proliferation of histiocytes with lymphophagocytosis (emperipolesis), which is a characteristic feature in RDD. In lymphophagocytosis, intact lymphocytes, plasma cells and RBCs are engulfed by the histiocytes, which is the hallmark of RDD. With these classical findings on FNAC, a diagnosis of RDD can be made. Hence biopsy may be avoided. [1,4,5,6]. On IHC, these histiocytes show S100 and CD 68 positivity. [2, 6].

The differential diagnosis of RDD includes reactive lymphadenitis with sinus histiocytosis, Tuberculosis, Langerhans cell histiocytosis (LCH), Lymphoma, Hemophagocytic lymphohistiocytosis (HLH) and autoimmune lymphoproliferative syndrome (ALPS) with Massive Lymphadenopathy. [6,7,8,9]

Recommendation

RDD is a self-limited and specific clinical condition that has a nodal and extranodal presentation. Clinically it looks like lymphoma. The specific cytological features are diagnostic for RDD.FNAC plays a vital role in the diagnosis of RDD and avoiding unnecessary surgery.