Diagnosis of SternomastoidTumor of Infancy by Fine-NeedleAspiration CytologyBipin Kumar, M.D.* and Anju Pradhan, M.D.

Sternomastoid tumor of infancy, also known as fibromatosis collior muscular torticollis, is a benign fibroblastic lesion of thesternocleidomastoid muscle presenting as a firm, fusiform, non-tender neck mass of 1–3 cm in greatest dimension in theperinatal period. Various modalities are used for the diagnosisincluding radiographic studies, fine-needle aspiration cytology(FNAC), and open biopsy. We report eight cases of sternomas-toid tumor of infancy diagnosed by FNAC. The objective of thestudy is to present the role of FNAC in the diagnosis of sterno-mastoid tumor with its cytomorphological features. FNA wasdone by using 23-guage needle and 10 ml disposable plasticsyringe. The wet smears were fixed in 95% ethanol and proc-essed for Papanicolaou stain. The dried smears were stainedwith May–Grunwald–Giemsa stain. The smears were studied forcytomorphologic features. The age of the patients rangedbetween 2 and 10 weeks. Male: Female ratio was 1.6:1. Six ofeight had history of prolonged labor, two had history of breechpresentation, and three had history of forceps assisted vaginaldelivery. Cytologic findings included singly scattered andloose clusters of benign fibroblasts with moderate amount ofunipolar to bipolar cytoplasm and plumped, ovoid nuclei.Many multinucleated giant cells consistent with atrophic musclefibers were also seen. FNAC is a reliable, safe, and cost-effective method and can provide a rapid and reliable diagno-sis of sternomastoid tumor of infancy. Diagn. Cytopathol.2011;39:13–17. ' 2010 Wiley-Liss, Inc.

Key Words: sternomastoid tumor; fibromatosis colli; sternoclei-domastoid muscle; fine-needle aspiration cytology; benign fibro-blasts

Sternomastoid or sternocleidomastoid tumor of infancy

(SCMI) also known as fibromatosis colli is a benign fibro-

blastic lesion affecting the body of sternocleidomastoid

muscle (SCM).1–10 It is the most common cause of neck

mass in the perinatal period with an incidence of 0.4%

live births.1–3,5 The classic presentation is the presence of

firm to hard fusiform mass in the lower or middle portion

of the SCM.1–6 However, it can be anywhere along the

length of the muscle.1 The right side is more commonly

involved than left7 and male affected more than female.5,6

It is usually identified during the second to fourth week

of life.2–4 The swelling may increases in size for several

weeks, then stabilizes in size for few months and finally

diminishes spontaneously by 4–8 months.4,9,10 However

the lesion, that presents after 1 month of age may not

resolves but increases in size.1 Contraction of fibrous

tissue within the lesion can lead to tightening of the

muscle resulting into motion restriction and ipsilateral

head tilt or muscular torticollis also known as wry

neck.1,10 SCMI is the most common cause of congenital

muscular torticollis with incidence of 10–20% among the

cases.3,9 It has a characteristic appearance. The head is

rotated and tilted toward the side of mass and the chin is

turned away from the affected side.4,6,10 This is secondary

to fibrosis, shortening of the affected muscle and its

inability to keep pace with the growth of the normal mus-

cle.6,10 Persistent torticollis may develop into cranial or

facial asymmetry, if remain uncorrected.9,10 SCMI is

associated with increased incidence of musculoskeletal

disorder such as metatarsus adductus, hip dysplasia, and

talipes equinovarus.3,6 Hip dysplasia is an associated fea-

ture in approximately 2.4–10% cases and it ranges from

subluxation to dislocation.3 It involves more commonly in

the side of sternocleidomastoid fibrosis and severity of

it is correlated with the severity of the torticollis.3 In

addition, lytic clavicular lesions, ipsilateral mandibular

asymmetry, plagiocephaly, occipital condyle asymmetry,

elevation of the ipsilateral clavicle and shoulder, facial

deformities, postural cervico-thoracic scoliosis, and gas-

tro-esophageal reflux may be associated features seen in

the cases of SCMI.3,4,6,9,10

Department of Pathology, B. P. Koirala Institute of Health Sciences,Dharan, Nepal

*Correspondence to: Bipin Kumar, M.D., Department of Pathology, B.P. Koirala Institute of Health Sciences, Dharan, Nepal.E-mail: bipinkumar31@yahoo.co.in

Received 22 September 2009; Accepted 1 December 2009DOI 10.1002/dc.21316Published online 20 January 2010 in Wiley Online Library

(wileyonlinelibrary.com).

' 2010 WILEY-LISS, INC. Diagnostic Cytopathology, Vol 39, No 1 13

In this study, five clinically diagnosed and three other

neck lesions are diagnosed as SCMI by fine-needle aspira-

tion cytology (FNAC). The pathogenic mechanism, differ-

ential diagnosis and its cytomorphological features are

discussed.

Methods

Cases

Eight infants (age: 2–10 weeks) were sent for FNAC

from the department of otorhinolaryngology between the

period of August 2006 to March 2009 and diagnosed as

SCMI. Five of them were suspected clinically as SCMI,

two as tuberculous lymphadenitis, and the remaining one

as branchial cyst.

Methods

FNA was done with a 23-gauge needle and 10 ml dispos-

able plastic syringe. The wet smears were fixed in 95%

ethanol and processed for Papanicolaou stain, and the

dried smears were stained with May–Grunwald–Giemsa

stain. The smears were studied for cytomorphological fea-

tures.

Results

The details of clinical and cytological findings are given

in Table I. The swelling was noticed at age 1–8 week

while age at diagnosis was 2–10 weeks. The male to

female ratio was 1.6:1 (5:3). Birth history was found in

all cases. Seven were delivered by primiparous. Six of

eight had relevant obstetrical history with associated pro-

longed labor. Two had history of breech presentation, one

delivered by normal vaginal root whereas other by cesar-

ean section; three had history of forceps extraction and

the remaining one had history of prolonged labor with

normal vaginal delivery. Two patients had normal obstet-

rical history. Each of these patients had neck mass of 2–3

cm in greatest dimension, five on right side and three on

the left. The mass was found in the middle part in four

cases, in lower third in three cases and one had mass

located in upper portion of SCM. Two cases had torticol-

lis in addition to neck mass and one had fever (viral?).

Cytological Findings

Smear showed scant to moderate cellularity comprising of

scattered singly or loosely cohesive clusters of spindle

and plump fibroblasts with associated strands of collagen.

These cells had oval to elongated nuclei, evenly dispersed

fine granular nuclear chromatin and unipolar or bipolar

tail of cytoplasm. Naked or stripped nuclei were also

present (Figs. 1–3). Atrophic skeletal muscle fibers in the Table

I.Clinical

andCytological

Details

SN

Clinicalfeatures

Cytolog

ical

features

Age/sex

Obstetrical

history

Location

(neck)

Size

(cm)

Associated

symptom

sClinical

diag

nosis

Cellularity

Giant

cells

Fibroblast

Bare

nuclei

Collagen

Backgroun

dDiagnosis

115d/M

Primi,breech,prolonged

labor,

delivered

byCS

Rt,middle

third

2.0

��SCMI

Moderate

++

++++

++

++

Hem

orrhagic

SCMI

228d/M

Primi,norm

alvaginal

delivery

Rt,lower

third

2.8

Fever

TBLN

Scant

+++

+++

++

+++

Myxoid,

hem

orrhagic

SCMI

310w/F

Primi,prolonged

labor,

norm

aldelivery

Lt,middle

third

2.5

��TBLN

Moderate

+++

+++

+++

++++

Myxoid

stroma

SCMI

435d/M

Para2,breech,prolonged

labor,

norm

aldelivery

Rt,lower

third

2.5

��SCMI

Moderate

++++

++++

+++

+++

Hem

orrhagic

SCMI

526d/F

Primi,prolonged

labor,

forcepsextraction

Lt,middle

third

3.0

Torticollis

SCMI

Scant

++

+++

++

+++

Hem

orrhagic

SCMI

627d/M

Priminorm

alvaginal

delivery

Rt,upper

third

2.5

��Branchial

cleftcyst

Scant

+++

++++

++

+++

Hem

orrhagic

SCMI

714d/M

Primi,prolonged

labor,

forcepsextraction

Rt,middle

third

2.0

��SCMI

Moderate

+++

++++

+++

+++

Myxoid

stroma

SCMI

817d/F

Primi,prolonged

labor,

forcepsextraction

Lt,lower

third

2.0

Torticollis

SCMI

Moderate

++

+++

++

+++

Hem

orrhagic

SCMI

SN,serial

number;d,day;w,week;M,male;

F,female;

CS,cesarean

section;Rt,right;Lt,left;SCMI,sternomastoid

tumorofinfancy;TBLN,tuberculouslymphadenitis.

KUMAR AND PRADHAN

14 Diagnostic Cytopathology, Vol 39, No 1

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form of myofibers with cross striations and multinucleated

giant cells were also seen (Fig. 4).

Discussion

The pathogenic mechanism of SCMI is still not clear.

Mechanism includes fetal malposition, birth trauma, is-

chemic necrosis after vascular compression during birth,

infection, and the presence of endogenous factor.1–4,6–10

A birth trauma theory postulates about difficult labor and

delivery which cause tearing of the SCM with subsequent

bleeding, hematoma, fibrosis, and contracture.3,10 Infec-

tion theory postulates intrauterine infection of the muscle,

with subsequent myositis and fibrosis.3,4 A vascular com-

promise theory postulates arterial occlusion or venous sta-

sis during labor leading to vascular insult with subsequent

muscle infarction and fibrosis.2,3,6 None of these theory

confirm the features of SCMI as no evidence of acute

bleeding, hematoma formation, subacute or chronic blood

products, organisms or inflammatory cells are found.3,6

Proposed mechanism of injury consisting of localized

kinking or crushing followed by in utero ischemia, reper-

fusion, or neurologic damage of the SCM are also

found.1,3 Still another possible theory regarding the

growth as a peculiar hamartomatous process6 and role of

clonal chromosomal abnormalities are also proposed.8

Well-recognized association between the SCMI and pri-

miparous births, breech presentations, forceps deliveries,

and difficult labor are found.1,3,10 Most authors emphasize

the importance of obstetrical malposition, particularly

breech presentation as an associated factor.1,2,9,10 This

Fig. 4. Smear showing multinucleated giant cells (MGG; 340).[Color figure can be viewed in the online issue, which is available atwileyonlinelibrary.com.]

Fig. 1. Moderately cellular smear showing scattered singly or looselycohesive clusters of fibroblasts with associated strands of collagen andgiant cells (Papanicolaou; 320). [Color figure can be viewed in theonline issue, which is available at wileyonlinelibrary.com.]

Fig. 2. smear showing scant cellularity revealing bundle of collagenfibers, fibroblasts, stripped or bare nuclei, and giant cells (Papanicolaou;320). [Color figure can be viewed in the online issue, which is availableat wileyonlinelibrary.com.]

Fig. 3. Smear showing plumped oval to spindle shaped fibroblasts hav-ing bland nuclei and unipolar to bipolar tail of cytoplasm along with fewbare nuclei (Papanicolaou; 340). [Color figure can be viewed in theonline issue, which is available at wileyonlinelibrary.com.]

STERNOMASTOID TUMOR

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study also shows association of SCMI with primiparous

births (7/8), breech presentations (2/8), forceps deliveries

(3/8), and difficult labor (6/8).

The lesion represents benign but infiltrative process

with partial replacement of SCM by diffuse fibroblastic

proliferation.2,5,7 Muscle fibers divided by the proliferat-

ing fibroblasts undergo atrophy.2,7 The early diagnosis for

this lesion is important because it needs conservative ther-

apy.2,4 The diagnosis is often can be made by clinical his-

tory and physical examination.2 On examination, the mass

is mobile in horizontal plane and are free from overlying

skin, particularly when head tilt is found.2,9,10 If the head

tilt is minimal or absent and mass is poorly defined, fur-

ther evaluation is required.2

The differential diagnosis include various reactive and

benign process, and malignant lesions such as hemangi-

oma, lymphangioma, lipoma, lipoblastoma, teratoma, thy-

roglossal duct cyst, cervical lymphadnitis particularly

tuberculosis, congenital branchial cleft cyst, congenital

goiter, heteropic thyroid, accessory lobe of thyroid, lym-

phoma, neuroblastoma, embryonal rhabdomyosarcoma,

low-grade fibrosarcoma, nodular fascitis, and calcifying

aponeurotic fibroma.1–10 The malignant lesions require an

early diagnosis, so that immediate therapy can be insti-

tuted.4 The remaining benign conditions need delayed sur-

gical procedures unless the mass compresses the airway

or other vital structures.4 Diagnostic surgical procedures

are more invasive, expensive, inconvenient for the

patients and their parents, and may lead to complications

of cosmetic defects resulting from contracture bands and

hence, reserved for complicated cases.2 For early diagno-

sis and desirability, and to avoid surgery in this age

group, noninvasive diagnostic procedures have a great

value.4 Radiographic technique is useful in the diagnosis

of SCMI.4 Computed tomography (CT) and ultrasonogra-

phy (USG) can locate the tumor in the body of SCM, and

differentiate solid and cystic lesions.1–4,9,10 The typical

CT scan shows the mass to be part of the muscle.4,9 The

area of enlargement is usually in the inferior half of the

muscle.9 Calcification in the mass or rest of the muscle

remains absent, and the cervical spines remain normal.9

These investigative procedures eliminate congenital cystic

and lymphatic malformation from diagnostic considera-

tion.2 USG shows the well-defined noncystic ovoid or

fusiform homogenous mass as a part of the muscle.9 The

mass moves with the muscle and is usually isoechoic or

slightly hypoechoic to the rest of the muscle.9 USG can

help to rule out the thyroglossal duct cyst, lymphangioma,

and lymphadenopathy.9 It also gives idea about the nature

of the swelling whether it is due to inflammatory or

malignant process?9 The absence of calcification rules out

teratoma, neuroblastoma, hemangioma, and abscess.9 It

also distinguishes thyroid lesion from SCMI.9 Because it

can be difficult to differentiate SCMI from surrounding

tissue, using CT or MRI can be used to distinguish tumor

from muscle, fat, or even scar tissue.9 CT and MRI are

costly, require sedation and contrast administration, and

are more traumatic than USG.3,4 Hence, USG can be pref-

erable radiologic technique for evaluation of neck masses

in neonates.3,4 However, these procedures are costly and

not available in all hospitals.6

Fine-needle aspiration is minimally invasive, cost-effec-

tive, time saving, quick, safe way, and well-established

outdoor procedures for the evaluation and diagnosis of

head and neck masses.1–7 Clinical impression of SCMI is

readily and easily confirmed by FNAC at bed side and

thus avoid more invasive procedures.2 The cytomorphol-

ogy of it reveals spindle shaped fibroblasts having bland

ovoid nuclei or fusiform cells with unipolar or bipolar

wispy cytoplasm.1–7 Atrophic skeletal muscles, muscle

giant cells, and collagen fibers are seen in a clean or myx-

oid background.6 Neither inflammation nor necrosis is

seen.2,6 FNAC of neuroblastoma, rhabdomyosarcoma, and

lymphoma show small blue cells as compared with the

benign spindle cells of SCMI.1,2,6 These small round cell

tumor react with antibodies to neurone specific enolase,

myoglobin, and common leucocyte antigen, respectively.3

The cystic lesions can be ruled out on the basis of clinical

examination and USG findings.1 FNA can support and

confirm the diagnosis.1 FNA of branchial cleft cyst, thyro-

glossal duct cyst, and lymphangioma yield variable

amount of fluid.2 On microscopy, branchial cleft cyst

shows benign squamous cells and inflammatory cells in

the dirty background1; thyroglossal duct cyst shows squa-

mous or columnar cells and multiple cyst macrophages

with or without follicular epithelial cells1,2 and lymphan-

gioma shows modest number of lymphocytes, macro-

phages, and rare endothelial cells.1 Hemangioma yields

altered blood and shows blood elements, hemosiderin

laden macrophages, and endothelial cells. Teratoma

reveals mixture of different type of cells pertaining to dif-

ferent germ cell layers.1 Thyroid lesion shows follicular

epithelial cells and variable amount of colloid. Cervical

lymphadenitis shows lymphoid series cells and tuberculo-

sis shows granulomas with or without caseation. Mature

adipose tissue fragments are seen in lipoma and lipoblast

are seen in lipoblastoma.1,2 None of these lesions show

benign fibroblasts and atrophic muscle fibers or muscle

giant cells. The other fibroblastic lesion such as nodular

fascitis can be excluded by absence of inflammation and

edema in the background.2 Infantile fibromatosis and cal-

cifying aponeurotic fibroma show infiltration of skeletal

muscle with collection of immature fibroblasts. Infantile

fibromatosis is a more infiltrative process and not remains

confined to single muscle group as in SCMI.4 Calcifying

aponeurotic fibroma rarely involves cervical region in

older child and it shows calcification cytologically and ra-

diologically.3,4 Low-grade fibrosarcoma rarely affects the

KUMAR AND PRADHAN

16 Diagnostic Cytopathology, Vol 39, No 1

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neck and usually present as larger lesion which show

hypercellularity and cellular atypia.4,5

After the diagnosis is confirmed, the parents of infants

are reassured and therapy can be immediately started.1

The treatment modalities are dependent on the size of the

mass and the presence of torticollis.1 Most of the cases of

sternomastoid tumor resolves spontaneously in few

months or respond to conservative treatment including

physical therapy with heat, massage, stretching exercises

for the affected muscle, strengthening exercises for con-

tralateral muscle, and occasionally the use of neck braces

during sleep.1,9,10 If the lesion is detected early, therapy

instituted during the first month of life and continued for

at least a year; 90% of patients will have a permanent

correction of the deformity.3,9 Surgical treatment is re-

served for those cases in whom contraction persists

beyond 1 year of age and for those who develop craniofa-

cial abnormalities.3,9,10 Surgical procedures include distal

tenotomy to avoid craniofacial asymmetry, scoliosis, and

plagiocephaly; muscle lengthening and excision of the

SCM and surrounding muscle.9 In our study, seven of

eight cases get free from the swelling after conservative

therapy and still one remaining is in follow up.

Conclusion

FNAC is safe, rapid, cost-effective, reliable outdoor pro-

cedure for the diagnosis of SCMI which can alley the

anxiety of parents quickly and guide for earlier conserva-

tive treatment so that permanent correction of the defor-

mity could be done and surgery can be avoided in these

cases, which can be reserved for the patients who develop

craniofacial abnormalities or have contraction that persists

beyond 1 year of age.

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