cribriform - morular variant of papillary thyroid carcinoma ( cmv - ptc ) is a distinct ptc with a better prognosis .
the affected patients have shown both germline and somatic mutations of adenomatous polyposis coli ( apc ) genes . unlike classic ptc ,
we report a case of cmv - ptc in a patient with apc , comparing with its documented cytomorphology and discuss its useful cytomorphological features in discriminating from other thyroid neoplasms .
a 24-year - old female presented with altered bowel habits and bleeding per rectum was diagnosed with apc .
at the same visit , she was diagnosed to have a multinodular goiter on imaging .
hypercellular smears showed cells arranged in monolayer sheets , discohesive papillae , cribriform clusters , cell morules with scattered single cells in a clean background [ figure 1 ] .
cribriform clusters showed slit - like and oval - to - round empty spaces surrounded by broad anastomosing bars of cells .
the papillae had well - formed branching fibrovascular cores [ figure 2a ] , however , lacked sharp anatomical borders or nuclear palisading , unlike those seen in conventional ptc .
the cells of papillae showed discohesion and spindling at the borders instead . the cellular composition varied with columnar cells at the edges of cell clusters , spindle cells attached to fibrovascular cores of papillae , and polygonal cells with small indistinct nucleoli in monolayer sheets .
hypercellular smears showing monolayer sheets ( arrow ) with cribriform spaces ( star ) , discohesive clusters of cells ( arrow head ) and morules ( circle ) ( h&e stain , 100 ) ( a ) .
papillae with well - formed branching fibro - vascular cores ( arrow ) and discohesive cells ( arrow head ) ( h&e stain , 100 ) .
histology sections showing cribriform pattern ( h&e stain , 200 ) these cytomorphological features were unusual for conventional ptc .
they were suspicious ; however , were not the classic features of cmv - ptc documented in the literature .
therefore , it was placed in bethesda thyroid cytology diagnostic category 5 , suspecting a ptc variant .
the thyroid contained multiple , circumscribed whitish nodules , distributed in both lobes and isthmus .
immunocytochemical staining with beta - catenin and biotin as well have shown a value in cytological diagnosis .
a series of 18 cases describe varying cellular arrangements with papillary pattern , which had been the predominant pattern in three - fourths of described cases .
in contrast , papillae were rare in this case and those present showed cell discohesion with spindling at the edges instead of palisading .
tall cells and spindle cells described as individual cells in the case series were present at the edges of flat monolayer sheets and papillary structures respectively in this case .
the peculiar form of nuclear clearing , foamy / hemosiderin - laden histiocytes and background hyaline material additionally described in the case series were absent in this case .
lack of colloid has been a constant feature both in the case series and this case .
fascicular and solid patterns are described as additional architectural patterns in another series of five cmv - ptc cases .
even though some degree of nuclear clearing and occasional nuclear inclusions were present , classical ptc nuclear features were absent in this case and the nuclei in general appeared to be of a higher grade than those seen in conventional ptc .
the most salient features described in a series of another eight cases was the hypercellularity and papillary architectures in which the papillae have shown three - dimensional branching and prominent fibrovascular cores covered by single layers of cells with classical ptc nuclear features , unlike the papillae of this case .
five other cmv - ptc cases additionally describe classical ptc nuclear features and cohesive papillary structures .
additionally , they describe cells with abundant cytoplasm and distinct cell borders , which was additionally appreciated in some columnar and polygonal cells in this case .
therefore , the cytomorphology of the present case is somewhat dissimilar to the features already described and those include papillae with cell discohesion and spindling at the periphery , presence of columnar cells only at the edges of flat monolayer sheets , absence of classic ptc nuclear features with the nuclei appearing to be of a higher grade than in ptc and discernible mitotic activity .
varied cytomorphological appearance of cmv - ptc may raise the possibility of a range of differential diagnosis of ptc variants and other thyroid neoplasms .
the tall cell variant of ptc ( tv - ptc ) may resemble cmv - ptc when abundant columnar cells are seen on smears .
however , the varying cytological features and smaller number of tall cells in proportion in cmv - ptc will differentiate it from tv - ptc .
tumor necrosis that may be present in tv - ptc is not described in cmv - ptc .
the presence of architectural atypia and squamous morules raise the possibility of a diffuse sclerosing variant of ptc
. however , the absence of significant nuclear pleomorphism , psammoma bodies , and sclerosing stromal fragments will be helpful to differentiate cmv - ptc from this variant .
. however , nuclear stratification resembling metastatic endometrial / colonic carcinoma and the absence of classical ptc nuclear features will be helpful in differentiating it .
however , the constellation of cytomorphological features of cmv - ptc in the absence of characteristic dispersed / powdery chromatin pattern of mc will make this diagnosis unlikely .
sheets of cells with eosinophilic granular cytoplasm , distinct cell borders , nuclear clearing , grooves , and inclusions are common to both cmv - ptc and hurthle cell tumors hence , making their differentiation difficult . diagnosing cmv - ptc on smears would be challenging especially in view of its varied cytomorphological appearance
. however , the full cytomorphological spectrum of cmv - ptc , when appreciated , may be characteristic enough to allow its accurate diagnosis .
awareness of the varied cytomorphology of cmv - ptc avoids misdiagnosis , especially when it occurs sporadically , unassociated with fap .
diagnosed apc patients , especially those with concurrent thyroid enlargement require exclusion of cmv - ptc , which has a recognizable cytomorphology and a favorable outcome .
 cribriform - morular variant of papillary thyroid carcinoma ( cmv - ptc ) , which has a better prognosis , is seen mostly in the setting of familial adenomatous polyposis ( fap ) . 
 the cytomorphology of cmv - ptc is diverse ; hence , it could be mistaken for other thyroid neoplasms with bad prognostic outcome . 
 this case is of a 24-year - old female diagnosed with polyposis coli found to have thyroid nodules at screening ultrasonography . 
 aspirated thyroid smears were hypercellular with epithelial cells arranged in monolayer sheets , papillae with discohesion , and spindling of cells at the edges , cribriform clusters , and cell morules . 
 individual cell morphology ranged from polygonal , tall columnar to spindle cells . 
 nuclei were round - to - oval with coarse chromatin , indistinct nucleoli , and mitotic figures . 
 nuclear inclusions and grooves were rare and colloid was sparse . 
 cytomorphology was suspicious , however , was not classical of cmv - ptc documented so far . 
 subsequent histology confirmed a cmv - ptc . 