Sir,

Extramedullary plasmacytoma (EMP), either nodal or extra-nodal has been defined as an autonomous proliferation of monoclonal plasma cells exhibiting varying stages of maturation and producing a localized mass or resulting in diffuse infiltration. [1] It accounts for 2% of all extramedullary plasma cell tumors and only 0.08% of all plasma cell neoplasms. [1] We report herein an extremely rare case of primary lymph node plasmacytoma (PLNP), in a 38-year-old male who presented to our hospital with a chief complaints of fever of 2 years duration associated with nonprogressive swelling in right side of neck since 2 months. On examination, the swelling showed 3-4 matted lymph nodes forming a nontender mass of about 1.5 × 1.5 cm in size. Ultrasound examination revealed features of reactive lymphadenopathy. The hematological and biochemical investigations of the patient were within normal limits. A bone marrow examination revealed normal bone marrow study with plasma cells of about 6%.

Fine-needle aspiration cytology (FNAC) performed on the lymph node mass showed cellular smears exhibiting both mature and immature plasma cells including myeloma cells scattered singly and arranged in small clusters along with presence of numerous neutrophils in the background. Binucleate and multinucleate forms were also present, plasma cells showed prominent eccentric nuclei, coarse chromatin, perinuclear halo and basophilic cytoplasm, while myeloma cells had high N:C ratio, fine chromatin, prominent nucleoli and little or no halo [Figure 1]a and b. A diagnosis of PLNP was made on cytology.{Figure 1}

Primary lymph node plasmacytoma is rare entity and in order to diagnose the same there should be no evidence of nodal or nonnodal extramedullary plasma cell proliferation elsewhere and absence of malignant lymphoma component. [2] The present case shows no other site of plasma cell proliferation with no clinical, radiological, and laboratory evidence of plasma cell dyscrasia, thus our case satisfies the criterion for PLNP. The differential diagnosis to be considered in case of PLNP includes: [3]

Reactive lymph node plasmacytosis, which will show mainly, mature plasma cellsLymphoplasmacytic immunocytoma, which microscopically shows presence of small lymphocytes mixed with lymphoplasmacytoid cells and plasma cellsMetastasis of an EMP or of a multiple myeloma, and from a lymph node involved by plasma-cell leukemia.There was no evidence of multiple myeloma in our case as bone marrow study was normal and no evidence of paraproteinemia was present. There was no evidence of plasma cell leukemia on peripheral smear and bone marrow examinationDiffuse large B cell lymphoma with plasma cell differentiation shows microscopically, cells varying considerably in size with nuclei, which are round, indented and irregularly folded: The features, which were not present in our casePlasmablastic lymphoma is seen in immunocompromised patients and is limited to oral cavity and jaw and aggressive in nature.

Other sites of occurrence of EMPs are in upper aerodigestive tracts including the nasal cavity, sinuses, oropharynx, salivary glands, larynx, and breast representing 80% of the reported cases. [4] Menke et al. studied largest series of PLNP (n = 25). [3] PLNP clinically behaves in better manner than other EMP, as it may manifest with disseminated lymph node spread but does not exhibit metastasis to bone marrow in comparison to other EMP which usually metastatize to bone marrow. [3] PLNP is cured by surgical excision or local radiotherapy. [2] PLNP similar to other EMPs has better prognosis and survival than patients of multiple myeloma. [3],[5] Cytological evaluation of plasmcytomas on FNAC offers rapid and reliable diagnosis on which prompt treatment decisions can be made.