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Paper text:
granular cell tumors ( gct ) are uncommon soft tissue neoplasms that may be asymptomatic or may present as a slow growing nodule .
we present a case of granular cell tumor in the right inguinal region misdiagnosed as a reactive lymph node on cytology .
a 63-year - old male presented with swelling in the right inguinal region for the past 10 years with a sudden increase in size since two months . on examination , a single , firm three cm swelling was felt in the right inguinal region .
no other lesion such as an ulcer or swelling was noted in the right leg or thigh .
there was no history of fever , rigors and loss of weight or appetite in the recent past .
an ultrasonogram of the right inguinal mass showed circumscribed hypoechoic mass suggestive of a lymph node shadow .
cytosmears examined were moderately cellular with dual cell population , composed predominantly of oval to polygonal cells with abundant cytoplasm and round bland nuclei resembling histiocytes [ figure 1 ] .
the background showed few discrete round cells with round nuclei and scanty cytoplasm suggestive of mature lymphocytes [ figure 1 ] .
no precursor lymphoid cells were seen on cytosmears . in correlation with clinical and image findings , an impression of reactive lymph node
a clinical follow - up and excision was advised if clinically suspicious or lesion further increased in size .
( a ) moderately cellular cytosmear showing clusters of cells with histioid appearance , lymphoid cells and few bare nuclei ( mgg , 100 ) ; ( b ) cytological smear with loose clusters of oval to polygonal cells having basophilic granular cytoplasm ( mgg , 200 ) an excision biopsy was performed which showed skin with a neoplasm located in lower dermis and subcutis .
individual cells appeared round to oval with abundant granular eosinophilic cytoplasm and centrally placed bland nuclei [ figure 2 ] .
immunohistochemistry showed s100 positivity in nucleus and cytoplasm ( [ figure 2 ] inset ) .
section show diffusely arranged tumor cells with granular eosinophilic cytoplasm intervening adnexal structures and presence of lymphoid aggregate ( h and e , 100 ) ; inset show tumor cells showing cytoplasmic and nuclear immunopositivity for s100 protein ( ihc , 100 )
granular cell tumor is a rare benign tumor arising predominantly in skin , subcutaneous tissues and tongue .
they may occur at any age , but commonly affects third to fourth decades of life .
generally , these are isolated lesions , but can be multiple in about 15% of cases .
usually , these tumors behave in a benign fashion , but malignant variant can also occur de novo or from transformation of a benign one . earlier gct was proposed to be derived from immature skeletal muscle cells ( hence , the term granular cell myoblastoma was given ) . however , later ultrastructure and immunohistochemistry studies have proven it to be of schwannian differentiation .
granular cell tumors show non - specific features on mri and may only be useful in assessing precise location of tumors which is essential for preoperative evaluation . in our case study , only an ultrasonogram was done . in general ,
cytological smears of gct show moderate to high cellularity with uniform appearing large cells arranged in syncitium and as isolated cells .
cytoplasmic granules are positive for periodic acid schiff stain and resistant to diastase . rarely , intranuclear inclusion has also been reported .
the granularity in cytoplasm of tumor cells is due to accumulation of secondary lysosomes resulting in its typical appearance on microscopy and thus deriving its name . in our case , due to the presence of lymphoid cells , the lesion was mistaken for a lymph node and the granular cells
were incorrectly identified as histiocytes on cytology . since it was a long - standing inguinal swelling with mild increase in size for the last two months
on reviewing the cytosmears , the larger cells appearing as histiocytes were definitely very granular and this is not a feature of sinus histiocytes .
misdiagnosis , in our case , was due to several reasons , foremost being the site of occurrence , clinical and radiological opinion of enlarged lymph node and finally misinterpretation of cytosmears .
cytological smears in our case showed mature lymphocytes and histopathology of the excised tissue showed features of granular cell tumor with many lymphoid aggregates .
this finding suggests that lymphocytes can sometimes feature in cytological smears of gct and can confuse the pathologist .
another feature on cytology that can further confound is the occurrence of stripped nuclei from tumor cells of gct resembling nucleus of lymphocyte .
granular cell tumor can rarely occur within a lymph node and it is important to know this fact to avoid a mistaken diagnosis of a metastatic tumor .
cell block is a useful technique that provides additional information from cytological specimen as it displays microhistology which can be further utilized for immunohistochemical studies . in the present case ,
our case further emphasizes that cell blocks should be considered in image guided aspiration as the material obtained in such cases is through a specialized invasive technique and a repeat aspiration would be cumbersome task .
we present this case to create awareness among the cytologists regarding the difficulties encountered in the cytodiagnosis of granular cell tumor .
the possibility of granular cell tumor should be considered when viewing single and cluster of large cells with abundant eosinophilic granular cytoplasm and vesicular nuclei on cytology .
a 63-year - old male presented with sudden increase in size of a right inguinal swelling which was present for the past 10 years . clinical diagnosis of inguinal soft tissue mass / lymph node enlargement was made and patient was investigated further for a conclusive diagnosis . 
 ultrasound examination suggested it to be a lymph node and guided fine needle aspiration cytology was performed . 
 cytology was suggestive of a reactive lymph node . 
 subsequently , an excision biopsy was performed that revealed a granular cell tumor with many lymphoid aggregates . 
 on reviewing the cytosmears , we realised that the granular neoplastic cells were mistaken for histiocytes ; and the lymphoid background and bare nuclei mislead us to consider it a reactive lymph node . 
 since granular cell tumor can occur almost anywhere , a careful examination of cytosmears and knowledge of its distinctive cyto - morphological features would be helpful in providing an accurate diagnosis on cytology .