Pediatric tumors

Introduction

Congenital masses are the product of abnormal developmental process. They are always present at birth, though depending on the size and location, they may elude diagnosis until the child is older. They can be composed of multiple tissue types and present as a solid, cystic, or vascular mass. Only in rare instances are the masses malignant, though if not treated properly there may be a potential for future malignant transformation.

Introduction

In normal development, the branchial arches fuse during the first 3–6 weeks of gestation. During this complicated process, any aberrant fusion may lead to the formation of branchial cleft remnants. The remnants are named by the numbered branchial cleft that they are derived from and have a relatively consistent anatomy. Branchial cleft remnants are present at birth but can grow over the course of early childhood as the cysts expand, or present as a draining sinus, and have high rates of infection. Surgical management is the mainstay of treatment.

Basic science/disease process

These structures present as cysts, internal or external sinus tracts, cartilaginous structures, or solid masses. These anomalies are often found in the anterior neck, within the anterior cervical triangle. While the pathway of these remnants is relatively consistent, the individual anomaly can be highly variable depending on the extent of the abnormal tissue left along the tract ( Fig. 33.1 ).

Diagnosis/patient presentation

The first branchial cleft anomaly is located near the external auditory meatus with a cleft or sinus extending to the angle of the mandible and then continuing to the patient’s midline. They account for 5%–25% of all branchial cleft anomalies ( Fig. 33.2 ).

The second branchial cleft remnant originates at the sternocleidomastoid (SCM) sternal origin and continues along the anterior SCM border. It remains lateral and then superior to the hypoglossal and glossopharyngeal nerves and terminates at the tonsillar fossa. These anomalies are the most common type of remnants, accounting for 40%–95% of these anomalies ( Fig. 33.3 ).

The third branchial cleft anomaly is diagnosed as a sinus tract at the anterior border of the SCM and travels deep into the neck towards the carotid artery, passing through the thyrohyoid membrane. This sinus continues towards its origin at the inferior laryngeal pyriform sinus, passing above the superior laryngeal nerve. These account for only 2%–8% of all branchial cleft anomalies.

The fourth branchial cleft anomaly presents as a sinus at the medial lower SCM border and passes deep to the carotid artery. It then can either loop around the aortic arch (left-sided anomaly) or subclavian artery (right-sided anomaly). The recurrent laryngeal and hypoglossal nerves run deep to the sinus tract, which terminates at the laryngeal pyriform sinus apex. These are the most rare type of cleft cysts representing approximately only 1% of all masses.

Treatment/surgical technique

While present at birth, many of these are initially small and are not diagnosed until early childhood. Physical exam demonstrates a small opening of the sinus tract, a palpable mass (cystic or solid), or remnants of cartilaginous structures. The sinus opening may have intermittent drainage and can present with infection. A CT scan or MRI is recommended for surgical planning to demonstrate the extent of the sinus.

Surgical excision is the treatment of choice for all lesions. Methylene blue may be injected into the sinus to assist with dissection. Identification of all nerves and arteries in the neck that are adjacent to the sinus is essential to preservation of function.

Outcomes, prognosis, and complications

While surgical resection is definitive, recurrence is possible if even a small portion of the sinus tract is left behind. Previous infections may complicate the resection as tissue planes are scarred around the sinus tract or cysts.

Introduction

Dermoid cysts are congenital remnants of embryonic germ cells that have been caught between two fusing layers of tissue. These abnormally located cells generate a cyst filled with an oily substance that continues to grow faster than the child does. They have a predilection for the head and neck but are seen everywhere on the body. Diagnosis and treatment of these dermoid cysts depends on their location and extent ( Fig. 33.4 ).

Basic science/disease process

Dermoid cysts form as a sequestration of neuroectoderm and somatic ectoderm during embryogenesis. Histologically, they are lined with stratified epithelium. These cysts are composed of ectodermal tissue, which differentiates into sebaceous glands and epithelium. They produce sebaceous material that fills the cyst and may grow hair inside the gland as well.

For intradural dermoids, these can occur anywhere from the occiput to the sacrum. Nasal dermoids are formed between the third and eighth week of embryogenesis from the neural groove. The cyst represents a persistent connection between the foramen cecum and the fonticulus nasofrontalis. They are located anywhere between the glabella and the base of the columella. Intracranial connections have been noted. Periorbital dermoid cysts, or extra angular dermoids, are located at the superior lateral orbital brow at the level of the frontozygomatic suture. Intracranial extension at this location is extremely rare. A more medial superior orbital location of these dermoid cysts is less common but may represent a variation of a frontonasal dermoid. Additionally, dermoid cysts can be found in the neck region, generally in the midline.

Diagnosis/patient presentation

Dermoid cysts present as firm, often mobile, cystic lesions. Frequent infections may be present. As the cysts are a closed space, as they fill with sebaceous material they continue to expand over childhood. Erosion of surrounding structures, including cranial bone, nasal cartilage, or soft tissue is common in larger cysts.CT scans should be used for any dermoid cysts located in the midline to rule out intracranial connections and differentiate from encephaloceles or gliomas. MRI is more useful for intracranial dermoids to evaluate connections to underlying neural structures.

Treatment/surgical technique

Nasal dermoids

Surgical planning depends on the extent of the nasal dermoid. For extracranial dermoids of the nasal tip and dorsum, an external rhinoplasty approach is preferred. Glabellar lesions may be approached either directly in a transcutaneous fashion or via a coronal incision to minimize anterior scarring ( Fig. 33.5 ). Dermoids of the nose/midline with deep extension require a more aggressive approach. Dermoids of the columella often extend along the anterior nasal spine and may bisect the septum, requiring a circumscribed removal of the sinus tract. Nasal dermoids with intracranial extension require a combined intracranial and extracranial approach to ensure all components are removed.

Nasal reconstruction may need to occur at the time of resection. If significant nasal cartilage is removed with the sinus, additional cartilage grafting from the rib or auricular sites may be necessary ( Fig. 33.6 ).

Outcomes, prognosis, and complications

Complete surgical excision has a high rate of success. Any component of the dermoid cyst that remains after surgery has the potential to induce a recurrence. For those in the nasal and intracranial location, recurrence is associated with abscess formation, meningitis, CSF leakage and significant deformity.

Introduction

Thyroglossal duct cysts are the most common congenital tumors of the anterior cervical region. These represent the persistent embryological remnant of the descending thyroglossal duct. They are located in the midline of the neck and from the base of the tongue to the level of the hyoid.

Basic science/disease process

The thyroid gland begins development at the foramen cecum during the third week of gestation. While the original position of the gland is at the base of the tongue, it descends along the pharynx until it encounters the second branchial arch. The fusion of this arch pushes the gland anteriorly where it passes the hyoid bone. Along this pathway, the ductal tissue differentiates into thyroid gland tissues. The final glandular tissues remain anterior to the hyoid bone, but the ductal tissue along this pathway should normally degenerate. Any residual glandular tissue along this pathway that does not involute will form a thyroglossal duct cyst. This tissue is lined with columnar, ciliated, or squamous epithelium.

Diagnosis/patient presentation

The thyroglossal duct cyst presents as a mass in the anterior neck at the level of the hyoid bone. A lingual thyroid would present as a large mass on the posterior superior tongue that may be visible during mouth opening ( Fig. 33.7 ). During swallowing, the mass moves with the bone due to its tethered location. These masses are soft, mobile, and painless. Infection may occur in these masses, which can lead to rupture and the formation of a thyroglossal duct sinus.

Treatment/surgical technique

Surgical excision is recommended for all thyroglossal duct cysts or remnants. Pre-surgical workup includes a CT scan to evaluate the extent of the sinus. A hormone evaluation or thyroid scan should be used to demonstrate if the thyroglossal duct cyst is a functional endocrine gland so that appropriate postoperative thyroid hormones can be administered. A Sistrunk technique uses a direct incision over the cyst followed by dissection up to the foramen cecum. A segment of the hyoid bone is often removed with the ectopic gland.

Outcomes, prognosis, and complications

With complete resection of the mass using the Sistrunk technique, recurrence rates are documented at <5%. If a portion of the mass is left behind, most often at the base of the tongue or the foramen cecum, recurrence is more likely.

Introduction

Leiomyomas are benign smooth muscle tumors that have been noted all over the body. While most commonly intra-­abdominal, these can arise from any visceral organ space and present as a soft-tissue mass.

Basic science/disease process

Cutaneous leiomyomas are rare and defined histologically by the presence of smooth muscle cells with calcifications and proliferations of spindle cells. These cells often have cigar-shaped nuclei and are stained for smooth muscle actin (SMA). Leiomyomas are benign but a suspicion for malignancy for any rapidly growing masses should necessitate excision. Patients with multiple cutaneous leiomyomas should be evaluated for possible Reed syndrome or hereditary leiomyomatosis with renal cell carcinoma.

Diagnosis/patient presentation

Leiomyomas present as smooth, deep soft-tissue masses originating off of the tunica media of blood vessels or the arrector pili musculature of hair follicles. Smooth muscle of the genital region, including the scrotum, labia, or nipple, have also been noted. Isolated leiomyomas are solitary dermal nodules that are rarely painful. Biopsy of the lesion and histology should confirm the diagnosis. MRI may be added if larger lesions are noted or to evaluate the extent of the mass.

Treatment/surgical technique

Surgical excision remains the gold standard. Additional treatment options for smaller lesions including CO ₂ laser or cryosurgery have been described. Medical management with nifedipine, nitroglycerine, or doxazosin have been used to reduce contraction of the smooth muscle for symptomatic or pain control if surgery is not an option.

Outcomes, prognosis, and complications

While leiomyomas are benign, surgical resection has a high rate of recurrence. Pharmacological treatment of symptoms including pain may be helpful for some patients.

Introduction

Infantile myofibromas or myofibromatosis is the most common fibrous tumor of infancy. Some 88% of cases present before the age of 2 with tumors ranging in size from 2 to 7 cm.

Basic science/disease process

Myofibromas present at birth and are histologically diagnosed with bundles of myofibroblasts or undifferentiated cells with irregularly branching hemangiopericytoma-like blood vessels.

Diagnosis/patient presentation

Solitary cutaneous myofibromas are diagnosed as an expansion of the dermis or a subcutaneous nodule and may appear as an ulcer, wart, or rubbery mass ( Fig. 33.8 ). Myofibromas are more often diagnosed in male infants and can involve the head, neck, or trunk. The myofibromatosis type can present anywhere in the soft tissue or viscera. Diagnosis is made with full body MRI to evaluate the extent of the lesion(s). Biopsy for histology provides confirmation.

Treatment/surgical technique

Infantile myofibromas may undergo spontaneous resolution. Larger isolated lesions or those impacting function require emergency surgical resection. Reconstruction is tailored to the site of resection and overall health of the infant. Reports of use of chemotherapeutic regimens have also demonstrated promise for multicentric disease.

Outcomes, prognosis, and complications

Patients whose myofibroma undergoes complete resection or involution have excellent prognosis. For patients with multicentric myofibromatosis, mortality rates are noted at 33%–75%, with organ involvement (cardiac, hepatic, renal) having a worse prognosis.