fibromatosis colli ( fc ) also known as sternocleidomastoid tumor , a self limiting lesion , presents as a firm to hard , immobile , fusiform swelling in the lower or middle portion of the sternocleidomastoid muscle and usually appears within the first few weeks of life . birth injury is supposed to play an important role in the pathogenesis , which is otherwise debatable as some of the cases do not have any history of birth injury . as the treatment of fc is usually conservative and avoids surgical procedures by employing physiotherapy , the diagnostic , noninvasive technique of fine - needle aspiration cytology ( fnac ) becomes important . fc has to be differentiated from congenital lesions , inflammatory lesions , neoplastic conditions  both benign and malignant  and other forms of infantile fibromatosis that may occur at that site . fc can be differentiated from other forms of infantile fibromatosis on the basis of the clinical features such as age , site , infiltrative pattern , and cytological features such as bland - appearing fibroblasts , degenerative , atrophic skeletal muscle , and muscle giant cells without inflammatory cells in a clean background.[26 ] in contrast to other forms of fibromatosis , a noninvasive , conservative management is usually the line of treatment for fc in most of the cases . fnac is a noninvasive method of diagnosis of fc that is thus useful in its management . we report here a case of a one month - old child with fc diagnosed by fnac and treated conservatively . a one month - old , male child delivered by forceps was being treated for right sided erb 's palsy in the physiotherapy department . at the time , a 22 cm , firm to hard swelling was noticed in the left side of the neck at the anterior aspect of the sternocleidomastoid muscle along with restricted mobility . the sheets of cells showed streaming in foci and the cytoplasm was eosinophilic with plump nuclei . also seen were atrophic skeletal muscle fibers and regenerating muscle giant cells [ figure 2 ] . single and sheets of spindle - shaped cells with atrophic muscle fibers ( h and e , 400 ) atrophic skeletal muscle fibers and regenerating muscle giant cells ( h and e , 400 ) fc is a self - limiting , benign tumor of infancy , presenting shortly after birth . the cause of the growth is debatable , but is usually associated with difficult or assisted labor and breech deliveries . birth injury resulting in ischemia may be the likely cause but it may also be probable that the growth is the cause rather than the effect of abnormal labor . another theory is that the growth is a peculiar , hamartomatous process that is unrelated to birth injury or vascular impairment . clinically , fc has to be differentiated from congenital lesions such as branchial cleft cysts , thyroglossal duct cysts , inflammatory lesions like tuberculous lymphadenitis , benign neoplastic conditions like hemangioma , cystic hygroma , lipoma , and malignant neoplasms like neuroblastoma , rhabdomyosarcoma , and lymphoma . a simple the cytomorphological features of fc are distinct with bland - appearing fibroblasts and degenerative , atrophic skeletal muscle in a clear background without any evidence of inflammation or hemorrhage . large numbers of mature and immature skeletal muscle fibres , muscle giant cells ; numerous , plump fibroblasts ; and collagen have been found along with a number of bland , bare nuclei in the background . [ 26 ] other infantile fibromatosis which tend to resemble fc can be differentiated on the basis of clinical features such as age , site , and infiltrative pattern and also , based on certain cytological features . cytologically , fc is differentiated from nodular fasciitis by the pleomorphism of proliferating fibroblasts and myofibroblasts with ovoid or kidney - shaped nuclei . bi- and multinucleated forms may be seen in a myxoid background along with inflammatory cells . other infantile fibromatoses can be differentiated on the basis of clinical features such as age , site , and infiltrative pattern and based on cytological features including collagen fragments and spindly nuclei . fc can be diagnosed by fnac , a noninvasive procedure , with newer , nonsurgical treatment procedures resulting in the regression of the lesions in 90% of cases .
fibromatosis colli is a peculiar , benign fibrous growth of the sternocleidomastoid that usually appears during the first few weeks of life and is often associated with muscular torticollis . 
 fibromatosis colli ( fc ) is seen in children born after difficult , prolonged labor , assisted delivery , and breech deliveries . 
 clinically , fc has to be differentiated from congenital lesions , inflammatory lesions , and neoplastic conditions  both benign and malignant  that may occur at that site . fine - needle aspiration cytology ( fnac ) is a simple technique that will help in excluding the above conditions and also in avoiding surgical procedures . 
 fibromatosis colli also resembles other forms of infantile fibromatosis , but its behavior , microscopic appearance , and its treatment distinguish it from other forms of infantile fibromatosis . 
 in contrast to other forms of fibromatosis , a noninvasive , conservative management is usually the line of treatment for fc in most of the cases . 
 fnac is a noninvasive method of diagnosis of fc that is thus useful in its management . 
 we report here a case of fibromatosis colli diagnosed by fnac .