Fig. 4.1
Finding a new bump while washing hair
4.2 Diagnostic Testing
Once the child is referred to pediatric neurosurgery, the provider may order a computed tomography (CT) scan or a magnetic resonance imaging (MRI). It is not uncommon for newborns to undergo ultrasonography (US); however, ultrasounds are usually considered preliminary tests, and more eloquent testing is usually needed. CT scans are ordered judiciously because of radiation exposure to the growing cranium. Most pediatric facilities limit the amount of radiation by using specific formatting. CT scans are ordered to assess bony lesions, whereas MRIs are ordered to assess soft tissue lesions, as well as possible intracranial involvement. Swift and Trumble (1999) note that up to one third of patients with solitary nontraumatic lumps on the head have some degree of intracranial extension.
Lesions that are noted to be in the midline or pedunculated (a stalk-like structure) should be evaluated with an MRI to assess the degree of probable intracranial extension. Midline structures that are pulsatile should be considered vascular and may be connected to a dural sinus (e.g., sinus pericranii). Further testing of possible vascular lesions may require specialized magnetic resonance imaging studies that include venous and arterial structures, known as MRI/MRVs. Arteriograms may also be performed (Table 4.1).
Table 4.1
Lesions of the skull and scalp overview
Lesion | Histology | Imaging features | Signs/symptoms | Treatment |
|---|---|---|---|---|
Cutis aplasia | Varies depending on depth of defect. Fibrovascular stomas and/or edematous stroma | N/A | Well-demarcated, noninflammatory ulceration | Smaller lesions will re-epithelialize without tx, larger lesions require surgical repair (skin grafting) |
Cranial dermal sinus tract | Stratified squamous epithelium | Inferiorly directed tract, enlarged foramen cecum may be present with nasal cranial dermal sinuses | Dimple usually located along the middle, with/without clear or yellow drainage | Surgical resection if intracranial |
Epidermoid/dermoid cyst | Squamous epithelium and keratin, dermoids also include hair and sebaceous/sweat glands | Lytic with sclerotic margins and bone erosion | Soft or hard, nonmobile nodule. Usually appears over suture lines | Surgical resection |
Ewing’s sarcoma | Compact and uniform cells with distinct nuclei. Sheets of round blue cells with increased nucleus-to-cytoplasm ratio | Bone destruction with irregular and poorly defined borders, “onion-peel” arrangement. Associated soft tissue mass | Intermittent at site, worse at night. Size of tissue mass can fluctuate. Leukocytosis, anemia, fevers | Local radiation with systemic chemotherapy. Surgical resection depending on the site of the disease |
Fibrous dysplasia | Fibroblastic collagen mixed with immature woven bone | Sclerotic, cyst-like, or “ground glass” appearance | Painless, boney skull deformity | Conservatively followed or surgical excision if symptomatic |
Neuroblastoma | Sheets of neuroblasts with small round blue cells, dark nuclei, and little cytoplasm | “Sunburst” appearance of bone spicules with elevation in periosteum seen on CT. Often present near cranial suture lines in children | Headache, pain, fever. “Raccoon eyes” with orbital bone involvement | Radiation and chemotherapy |
Neurofibromas | Proliferation of all aspects of peripheral nerves. Wavy serpentine nuclei with pointed ends. Stromal mucin deposition and fibroplasia | Sphenoid wing dysplasia, pseudarthrosis | Axillary freckles, café au lait spots, dermal fibromas | Surgical excision |
Langerhans cell histiocytosis | Large cells with eosinophilic cytoplasm and irregular nuclei | Lytic or “punched-out” appearance, with/without soft tissue mass | Asymptomatic or with localized pain over a raised, soft, and tender area | Low-dose radiation, surgical excision, or conservative tx with immobilization (lesions of the spine and long bones) |
Osteoma | Similar to normal bone, decreased marrow | Hyperdense and expansile | Asymptomatic or with pain over lesion | Biopsy and/or surgical excision |
Osteoblastoma | Large epithelioid osteoblasts | Well-demarcated, mixed lytic/sclerotic lesion with enlarged diploe | Asymptomatic or with pain over lesion | Biopsy and/or surgical excision |
Sinus pericranii | Endothelial lining with congenital etiology. Connective tissue with traumatic etiology | Soft tissue mass with extracranial and intracranial venous communication seen with venogram. Associated skull defect | Compressible, painless mass. Enlarged in recumbent position and diminished in erect position | Surgical resection |
4.3 Neoplastic
The term neoplasm refers to an abnormal growth of tissue caused by the rapid division of cells that have undergone some form of mutation. Benign neoplasms are usually localized and do not invade other tissues, while malignant neoplasms are usually invasive.
Benign skull lesions are typically seen as a single lesion on radiographs, and CT scans or skull X-rays are typically performed as the bone is more clearly identified in these studies. Malignant lesions tend to have ragged margins and usually occur in multiples.
Benign
Examples of benign tumors of the skull include epidermoid and dermoid cysts, fibrous dysplasia, histiocytosis (eosinophilic granuloma), osteomas and chondromas, as well as neurofibromas. Benign vascular lesions include hemangiomas, sinus pericranii, encephaloceles, and aneurysmal bone cyst.
Acute neoplasms of the scalp are unusual in children; congenital lesions of the scalp are more common. Lesions that are not attached to the cranium may be referred to a pediatric plastic surgeon for evaluation. An example of an interesting and rare benign lesion of the scalp is cranial fasciitis (Halder et al. 2012).
Malignant
Malignant lesions of the skull include chordomas, sarcomas, neuroblastomas with inner osseous involvement, and some leukemias.
Malignant lesions of the scalp are rare, but there are a few examples of congenital lesions that could become malignant. These include nevus sebaceous lesions that could lead to basal cell carcinoma. Some moles or nevi could also become malignant.
4.3.1 Neurofibromas
Craniofacial neurofibromas can involve peripheral nerves of the face, orbit, and cranial base. Facial lesions can be disfiguring and are usually taken care of by plastic surgeons. Neurofibromas are seen in patients who have neurofibromatosis (NF), which is classified into two distinct clinical groups based on the pattern of clinical presentation. These are multisystem disorders.
4.3.1.1 Epidemiology
NF 1 is one of the most commonly occurring genetic disorders and is seen frequently in the neurology and neurosurgery clinic. It occurs in 1 in 3,000–4,000 people (Pollack 2008). It is an autosomal dominant condition with the effected gene on chromosome 17 (17q11.2). Spontaneous mutation is high, with 30–50% of cases representing new mutations.
NF2 is one tenth as common, affecting only 1 in 50,000 patients (Pollack 2008).
4.3.1.2 Evaluation
Children with NF1 often have lesions of the skin such as freckles in unusual places (i.e., axillary), multiple café au lait spots, or dermal fibromas. Eye lesions can include glaucoma, optic pathway gliomas, and Lisch nodules. Sometimes pulsatile exophthalmos is also present.
Children with NF 2 can present with either unilateral or bilateral cranial nerve VIII lesions. They may also present with a meningioma.
Neurofibromas of the scalp may be seen in NF 1 and sometimes NF 2.
Patients who have neurodermatoses are often screened with CT scan or MRIs. It is during the screening processes that lesions of the skull and scalp may be found. The Committee on Genetics of the American Academy of Pediatrics has published guidelines on how these children should be screened and monitored (Hersh and Committee on Genetics 2008).
Bony lesions of the skull in children with NF include sphenoid wing dysplasia seen on head CT scan. Other bony lesions include tibial bowing as well as pseudarthrosis.
4.3.1.3 Treatment
Focal, resectable, or symptomatic lesions are surgically removed. Other lesions are usually followed with routine radiographs. The nurse is mindful to observe for lesions that are growing or changing in characteristics. Clinical coordination includes making sure the children are seen by the appropriate disciplines including neurology, genetics, orthopaedics, and neurosurgery.
4.3.2 Fibrous Dysplasia
4.3.2.1 Etiology and Pathophysiology
Fibrous dysplasia is another example of a lesion that though benign can become malignant (Greenberg 2014). Normal bone is replaced with fibrous connective tissue. The abnormal tissue is composed of fibroblastic collagen, and it is mixed with immature woven bone.
The etiology is not clear. There are three types: (1) cystic, though not an actual cyst, there is widening of the diploe with thinning of the outer table and little involvement of the inner table; (2) sclerotic, usually seen in the skull base and facial bones; and (3) mixed.
Fibrous dysplasia accounts for approximately 2.5% of all bone tumors (Swift and Trumble 1999). It is most commonly seen at puberty and has equal distribution between boys and girls. As is seen with other bone tumors, the disease becomes more prominent during periods of growth.
4.3.2.2 Evaluation
Initially, the child presents with a progressive and painless deformity of the skull. Various parts of the craniofacial skeleton may be involved including the orbit and foramina of other cranial nerves. Thus, there is concern of visual impairment when it involves the orbit because of distortion of the globe. These children are usually seen by a craniofacial team (Fig. 4.2).
Fig. 4.2
Fibrous dysplasia seen on (a) MRI and (b) CT with bone windows
As this is a bony lesion, the most appropriate test would be a CT. On plain radiographs and on CT, the lesion has a “ground glass” appearance due to the spicules of woven bone. An MRI may be performed to rule out intracranial involvement, including the involvement of cranial nerves.
4.3.2.3 Treatment
These can be slow-growing lesions and may be followed conservatively. If the lesion is impairing vision or impedes other cranial nerves, surgical excision is planned.
A meta-analysis of surgery versus watchful waiting by Amit et al. (2011) looked at several trials, studies, and individual case presentations. It was determined that surgeons prefer “watchful waiting” if the patient was asymptomatic, and surgery would be preferred for those who were symptomatic (i.e., visual changes). Asymptomatic patients with lesions of the optic nerve who underwent optic nerve decompression usually had some loss of vision. Thus, it was determined that watchful waiting would be more appropriate for those patients without impaired vision.
4.3.3 Langerhans Cell Histiocytosis
Langerhans cell histiocytosis (LCH) is an entity that has been referred to as histiocytosis X or eosinophilic granuloma. When seen as a single lesion, it is classically known as eosinophilic granuloma.
LCH is a nonneoplastic type of histiocytic disorder that is most commonly characterized by a single lesion but also can be seen as multiple osteolytic bone lesions. Multiple lesions are more frequently seen in children under age 3 years.
LCH can be seen as a systemic entity, disseminating into the CNS and through the viscera. Lesions can present as skin lesions, pulmonary infiltrates, hepatosplenomegaly, and lymphadenopathy.
There is a subgroup of malignant histiocytic disorders, and these include the monocyte-related leukemias (acute monocytic leukemia, acute myeloid/myelomonocytic leukemia) and other tumors.
4.3.3.1 Etiology
LCH is a rare histiocytic disorder that accounts for 7–10% of all reported skull lesions. It is seen in all age groups but it is most common in children from 1 to 3 years of age. The incidence appears to be three to five cases per million children, which is the same as pediatric Hodgkin’s lymphoma, and in one to two cases per million in adults.
The genetics of LCH is not well defined at this time. There is no current evidence that relatives of the patients with this condition are at increased risk of developing it.
4.3.3.2 Pathophysiology
LCH is named because of a presumed derivation of the morphology similar to Langerhans cells, which are specialized dendritic cells found in the skin and mucosa.
Gene expression array data has shown that Langerhans cell is not the actual cell origin for LCH. Rather it is a myeloid dendritic cell that expresses the same antigens (CD1a, CD207) as the actual Langerhans cell.
A few studies reported evidence of viruses within the LCH lesions, but at this time, viral etiology debate is ongoing. It is now thought to be an inflammatory myeloid neoplasia because of two mutations found in up to 75% of all biopsies. Some studies support that LCH is a reactive condition due to immunological dysfunction stemming from regulatory T-cell expansion and a lack of mutations and tumor suppressor genes. However, there is also support that LCH is a neoplasm which comes from finding cancer-associated proto-oncogene mutations seen in a high percentage of LCH biopsies (McClain 2016).
4.3.3.3 Clinical Presentation
The areas of involvement vary with age. Acute disseminated multisystem disease is most commonly seen in children less than 3 years of age, while a more indolent disease involving the single origin is more common in older children and adults. Presenting symptoms in patients depend on the organ system involved. Most patients with bone marrow involvement are young children with diffuse disease in the liver, spleen, lymph nodes, and skin. LCH patients under 2 years of age with two or more “risk organs,” such as hematopoietic organs, have a poor prognosis.
4.3.3.4 Lytic Bone Lesions of LCH
Bone involvement occurs in the majority of patients with this condition. The most frequent sites of bony involvement are the skull (40–80%), femur, ribs, vertebrae, and humerus.
It is interesting to note that some lesions may be asymptomatic, while other patients may complain of pain in a localized area of the bone. Examination of the area usually reveals a lesion that is raised, soft, and tender to palpation. Skull radiographs typically demonstrate a lytic or “punched out” appearance with unequal involvement of the outer and inner tables. Typically there is a sclerotic rim. Sometimes there is an accompanying soft tissue mass (Fig. 4.3a–c).
Fig. 4.3
(a) A 12-year-old girl with recurrent frontal skull lesions from histiocytosis. (b) Intraoperative view of excision of skull lesions. (c) Excised lesion with the surrounding bone
4.3.3.5 Treatment
Treatment depends on presentation. For example, in cases where children have pain without neurologic deficit, immobilization may be tried (such as in lesions of the spine or long bones). Studies indicate that younger children may spontaneously regress with arrest of further bony destruction. The pain usually resolves when the disease arrests. Low-dose radiation is sometimes used for these lesions with good result.
Parent and Shiflett (2011) state that management of LCH skull lesions usually requires wide surgical resection. These lesions may be attached to dura and subcutaneous tissues and can be friable. These lesions can be persistent and recur. Chemotherapy or low-dose radiation may be considered.
4.3.4 Osteoma and Osteoblastoma
Osteomas are more commonly seen in young adults and rarely in children. These lesions have a distinctive appearance on CT of being hyperintense and expansile. If the lesions are essentially asymptomatic, they are followed. If surgery is performed, the entire lesion is removed and is repaired with a split-thickness graft (Swift and Sacco 2008).
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