Ventriculoperitoneal shunt induced neck mass mimicking sternocleidomastoid tumour: a previously unreported complication
- 1 Department of Paediatric Surgery, All India Institute of Medical Science, Bhopal, Madhya Pradesh, India
- 2 Department of Pathology, All India Institute of Medical Science, Bhopal, Madhya Pradesh, India
- Correspondence to Dr Reyaz Ahmad; reyaz.pediasurg@aiimsbhopal.edu.in
Abstract
Ventriculoperitoneal shunt (VPS) for hydrocephalus is associated with various complications. Torticollis due to shunt tract fibrosis is a rare complication of VPS that occurs years later after the initial operation. However, shunt track fibrosis that progressed to large neck mass, mimicking sternocleidomastoid tumour and causing torticollis is a previously unreported complication. This led to the restriction of neck movement and hemifacial hypoplasia. Complete excision of the mass restored neck movement.
Background
Ventriculoperitoneal shunt (VPS) placement is the most commonly performed neurosurgical procedures to treat most forms of hydrocephalus. Unfortunately, this procedure is associated with various complications.1 VPS complications are common in both paediatric and adult populations, with frequency ranging from 45% to 59% in different reports.2–5 However, shunt track fibrosis that progressed to large neck mass, mimicking sternocleidomastoid tumour, even after the removal of VPS is not reported until.
Case presentation
A 3-year-old boy was admitted with a problem of right side neck mass and torticollis for 1.5 years. The patient had a history of ventriculoperitoneal shunt surgery for porencephalic hydrocephalus done at 2.5 months of age. Two years after the procedure, the patient developed torticollis because of shunt tract fibrosis, for which VPS was removed elsewhere. After shunt removal, patient had no neurological symptoms, so replacement of shunt was not done. The shunt tract fibrosis progressively increased in size, forming a mass and restricted neck movement for last 1 year. The mother also noticed facial asymmetry.
On examination, patient was clinically well, hemodynamically stable, had spontaneous eye opening and no neurological deficit except right torticollis with obvious facial asymmetry and a large, oval, firm mass at right side of neck extending from mastoid region to chest, about 10×4 cm in size. The skin and underlying muscle were free from mass (figure 1).
Pre operative image of neck mass
Investigations
Contrast-enhanced CT (CECT) of the head revealed porencephalic cyst with mild dilated ventricular system (figure 2) and CECT of the neck region revealed a well-defined relatively hyperdense soft tissue mass in posterior triangle of neck extending from right mastoid region to right upper chest, abutting posterior margin of right sternocleidomastoid muscle figure 3.
Contrast enhanced computed tomography (CECT) of head revealed dilated ventricular system (A) and porencephalic cyst (B)
CECT neck region showing a well-defined relatively hyper dense soft tissue mass in posterior triangle of neck extending from right upper chest (A,B) to right mastoid region, abutting posterior margin of right sternocleidomastoid muscle (C,D).
Fine needle aspiration cytology of the mass was suggestive of the features of sternocleidomastoid tumour (fibromatosis colli).
Differential diagnosis
Clinically and fine needle aspiration cytology of the mass was suggestive of the features of sternocleidomastoid tumour (fibromatosis colli).
Treatment
Excision biopsy of the mass was planned. Informed consent was taken and patient was operated under general anaesthesia with position of extended neck and left lateral head position. Two step ladder transverse incisions were given, one at near upper extension of mass and second at lower neck. The mass was completely excised and sent for HPE (figure 4). Histopathological examination (HPE) revealed fibrocollagenous tissue with few multinucleated foreign body giant cell with engulfed granular refractile material in cytoplasm (silicone) and presence of chronic inflammatory infiltrate (figures 5 and 6).
Intra-operative image of excision of neck mass
Fibro collagenous tissue with foreign body giant cells (Haematoxylin and Eosin staining, 100x).
Foreign body giant cells with refractile material in the cytoplasm (Haematoxylin and Eosin staining,400X, long arrow indicating chronic inflammatory infiltrate as multi nucleated foreign body type giant cell with engulfed granular refractile material in cytoplasm (silicone material) and small arrow indicating granular refractile material.
Patient had an uneventful recovery and was discharged on postoperative day 5, with advice for neck physiotherapy and regular follow-up.
Outcome and follow-up
Follow-up till 12 months was uneventful, with restoration of neck movement and resolution of hemifacial hypoplasia (figure 7).
Post operative image (A) resolving hemi facial hypoplasia (B) post op follow up image with scar
Discussion
Sternocleidomastoid tumour of infancy is a self-limiting pseudotumour of infancy presenting with neck mass and restriction of neck movement. It is a benign proliferation of fibrous tissue within the sternocleidomastoid muscle leading to focal or diffuse enlargement of muscle.
Complications of VPS may occur anywhere along their course from the cerebral ventricle to the peritoneal cavity.4 The most common VPS complication or causes of shunt failure in both paediatric and adult population is shunt obstruction followed by infection, with infections tending to cause early shunt failures and catheter occlusion typically accounting for late shunt failures.1 Other less common complications included pseudocyst formation, under drainage and subdural haematoma formation due to over drainage. A rare complication is migration of the peritoneal end of shunt, including perforation of nearly every hollow viscous, including the stomach, gallbladder, vagina, scrotum, bladder, bowel, colon, pulmonary artery, diaphragm, cardiac ventricle, umbilicus, rectum, anus, and mouth have been described in the literature.4
Lee et al used the term ‘tract fibrosis’ for the findings of inflammatory tissue that result from scarring and/or calcinosis surrounding the VPS catheter. These fibrotic tissues usually take a tubular shape, mirroring that of the catheters tubular structure, hence the term tract fibrosis.5
The biopolymers used for shunts deteriorates with time, the structure of the polymer is altered by hydration leading to weak covalent bonds of the polymer chain which breaks, reducing the molecular weight of the polymer and certain soluble fragments are engulfed by macrophages. In the human body, silicone is able to resist chemical degradation and mechanical stress for several years.6 Irving et al studied the tissue reaction to pure silastic, silastic impregnated with 10% barium sulphate and 10% precipitated silver in rats. After 6 months, the implants had a thin, non-adherent fibrous sheath of hyaline acellular connective tissue and some fibroblastic proliferation. No differences were seen in the reactions to the various types of silastics.7
Inflammatory reaction or interaction with VPS material results in the formation of thick fibrous and calcified mass around shunt tube causing torticollis. The tract fibrosis usually improves with removal of the shunt.8 However, in this child, inflammatory reaction or interaction between VPS silicone material and tissue continued even after removal of shunt, resulting in progressive increase in size of the mass, hemifacial asymmetry and restriction of neck movement. The mass was excised, preserving the function of sternocleidomastoid, neck mobility and improvement in facial asymmetry with minimal skin scarring.
Learning points
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The possibility of this rare entity should be kept in mind as a complication of ventriculoperitoneal shunt (VPS).
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Surgical excision should be considered in patients with progressive increase in size of the mass and fibrosis even after removal of VPS, torticollis causing restriction of neck movement and hemifacial hypoplasia.
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Complete excision of the mass improves the neck mobility as well as the facial asymmetry.
Footnotes
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Contributors MKJ: drafting the article or reporting, acquisition of the data and clinical work. RA: conception and design of the article, planning and final correction. GG: pathological diagnosis and histopathology image. SP: collection and maintenance of the data, clinical work and care of the patient.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Patient consent for publication Parental/guardian consent obtained.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.
References
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