Patients come to clinical attention early in life (usually at birth or within the first few months), with a firm subcutaneous nodule at bridge of nose, or as a polypoid mass within the nasal cavity, or somewhere along the upper border of the nasal bow. If the patient presents with an intranasal mass, there may be obstruction, chronic rhinosinusitis, or nasal drainage. If there is a concurrent cerebrospinal fluid (CSF) leak, then an encephalocele is much more likely.

This lesion is separated into two types based on the anatomic site of presentation:

1. Extranasal (60%): Subcutaneous bridge of nose

2. Intranasal (30%): Superior nasal cavity

3. Mixed (10%): Subcutaneous tissues and nasal cavity (larger lesions)

Delayed motor development of infants affected by PVL has been demonstrated in multiple studies. One of the earliest markers of developmental delays can be seen in the leg movements of affected infants, as early as one month of age. Those with white matter injury often exhibit "tight coupling" of leg joints (all extending or all flexing) much longer than other infants (premature and full-term). Additionally, infants with PVL may not be able to assume the same positions for sleeping, playing, and feeding as premature or full-term children of the same age. These developmental delays can continue throughout infancy, childhood, and adulthood.

It is often impossible to identify PVL based on the patient’s physical or behavioral characteristics. The white matter in the periventricular regions is involved heavily in motor control, and so individuals with PVL often exhibit motor problems. However, since healthy newborns (especially premature infants) can perform very few specific motor tasks, early deficits are very difficult to identify. As the individual develops, the areas and extent of problems caused by PVL can begin to be identified; however, these problems are usually found after an initial diagnosis has been made.

The extent of signs is strongly dependent on the extent of white matter damage: minor damage leads to only minor deficits or delays, while significant white matter damage can cause severe problems with motor coordination or organ function. Some of the most frequent signs include delayed motor development, vision deficits, apneas, low heart rates, and seizures.

Various degrees of intensity and locations of epilepsy are associated with malformations of cortical development. Researchers suggest that approximately 40% of children diagnosed with drug-resistant epilepsy have some degree of cortical malformation.

Lissencephaly (to which pachygyria is most closely linked) is associated with severe mental retardation, epilepsy, and motor disability. Two characteristics of lissencephaly include its absence of convolutions (agyria) and decreased presence of convolutions (pachygyria). The types of seizures associated with lissencephaly include:

- persisting spasms

- focal seizures

- tonic seizures

- atypical seizures

- atonic seizures

Other possible symptoms of lissencephaly include telecanthus, estropia, hypertelorism, varying levels of mental retardation, cerebellar hypoplasia, corpus callosum aplasia, and decreased muscle tone and tendon reflexes. Over 90% of children affected with lissencephaly have seizures.

Patients with subcortical band heterotopia (another disorder associated with pachygyria) typically have milder symptoms and their cognitive function is closely linked to the thickness of the subcortical band and the degree of pachygyria present.

While nasal glial heterotopia (NGH) is the preferred term, synonyms have included nasal glioma. However, this term is to be discouraged, as it implies a neoplasm or tumor, which it is not. By definition, nasal glial heterotopia is a specific type of choristoma. It is not a teratoma, however, which is a neoplasm comprising all three germ cell layers (ectoderm, endoderm, mesoderm). As a congenital malformation or ectopia, it is distinctly different from the trauma or iatrogenic development of an encephalocele.

Pachygyria (from the Greek "pachy" meaning "thick" or "fat" gyri) is a congenital malformation of the cerebral hemisphere. It results in unusually thick convolutions of the cerebral cortex. Typically, children have developmental delay and seizures, the onset and severity depending on the severity of the cortical malformation. Infantile spasms are common in affected children, as is intractable epilepsy.

There are various symptoms of colpocephaly and patients can experience effects ranging from mild to severe. Some patients do not show most of the symptoms related to colpocephaly, such as psychomotor abnormalilities and agenesis of the corpus callosum. In some cases, signs appear later on in life and a significant number of children suffer only from minor disabilities.

The following list includes common symptoms of colpocephaly.

- partial or complete agenesis of the corpus callosum

- intellectual disability

- motor abnormalities

- visual defects such as, crossing of the eyes, missing visual fields, and optic nerve hypoplasia

- spasticity

- seizures

- cerebral palsy

Intracranial abnormalities include:

- Microcephaly

- Agenesis of the corpus callosum

- Meningomyelocele

- Lissencephaly

- Periventricular leukomalacia (PVL)

- Enlargement of the cisterna magna

- Cerebellar hypoplasia

Often, this disease evolves from a precursor lesion, usually a dysplastic nevus. Otherwise it arises in previously normal skin. A prolonged radial growth phase, where the lesion remains thin, may eventually be followed by a vertical growth phase where the lesion becomes thick and nodular. As the risk of spread varies with the thickness, early SSM is more frequently cured than late nodular melanoma.

The microscopic hallmarks are:

- Large melanocytic cells with nest formation along the dermo-epidermal junction.

- Invasion of the upper epidermis in a pagetoid fashion (discohesive single cell growth).

- The pattern of rete ridges is often effaced.

- Invasion of the dermis by atypical, pleomorphic melanocytes

- Absence of the 'maturation' typical of naevus cells

- Mitoses

The features of this syndrome affect the face, skin, brain and the body.

Face:

- downslanting palpebral fissures

- pointed chin

- prominent forehead

- proptosis

- thin upper lip

- wide nasal bridge

Skin:

- fragile

- hyperelastic

Brain:

- Low IQ

- Periventricular white matter lesions

Body:

The height, lower-segment, hand, and foot length are all greater than usual.

Until recently, nodular fasciitis have been considered a reactive process of uncertain cause. However, recent findings indicate that nodular fasciitis is a self-limited clonal neoplastic process (see below). Clinically, nodular fasciitis presents as a subcutaneous "growth" over a period of 3–6 weeks that eventually regresses. The lesion usually reaches a size of 2–3 cm. Larger lesions are unusual. Local recurrence has been described after simple surgical excision but it is rare.

Eccrine angiomatous hamartoma usually appear as a solitary nodular lesion on the acral areas of the extremities, particularly the palms and soles.

Nodular fasciitis, also known as nodular pseudosarcomatous fasciitis, pseudosarcomatous fasciitis, and subcutaneous pseudosarcomatous fibromatosis, is a benign soft tissue lesion most commonly found in the superficial fascia. The lesion commonly occurs in the first three decades of life. Upper extremities and trunk are the most common affected anatomical sites. Previous history of trauma may be present. Clinically and histologically, nodular fasciitis may be mistaken for a sarcoma.

Superficial spreading melanoma (also known as "superficially spreading melanoma") (SSM) is usually characterized as the most common form of cutaneous melanoma in Caucasians. The average age at diagnosis is in the fifth decade, and it tends to occur on sun-exposed skin, especially on the backs of males and lower limbs of females.

Infantile digital fibromatosis (also known as an "Inclusion body fibromatosis," "Infantile digital myofibroblastoma," and "Reye tumor") usually occurs as a small, asymptomatic, nodular, dermal fibrous proliferation at the extensor or lateral surface of a finger or toe.

Subcortical heterotopia form as distinct nodes in the white matter, "focal" indicating specific area. In general, patients present fixed neurologic deficits and develop partial epilepsy between the ages of 6 and 10. The more extensive the subcortical heterotopia, the greater the deficit; bilateral heterotopia are almost invariably associated with severe developmental delay or mental retardation. The cortex itself often suffers from an absence of gray matter and may be unusually thin or lack deep sulci. Subependymal heterotopia are frequently accompanied by other structural abnormalities, including an overall decrease in cortical mass. Patients with focal subcortical heterotopia have a variable motor and intellectual disturbance depending on the size and site of the heterotopion.

Focal nodular hyperplasia's most recognizable gross feature is a central stellate scar seen in 60–70% of cases. Microscopically, a lobular proliferation of bland-appearing hepatocytes with a bile ductular proliferation and malformed vessels within the fibrous scar is the most common pattern. Other patterns include telangiectatic, hyperplastic-adenomatous, and lesions with focal large-cell dysplasia. Rarely, these lesions may be multiple or can occur as part of a syndrome with hemangiomas, epithelioid hemangioendothelioma, hepatic adenomas, fibrolamellar hepatocellular carcinoma, vascular malformations of the brain, meningiomas, and/or astrocytomas.

Giant-cell tumor of the tendon sheath, also known as giant-cell synovioma and localized nodular tenosynovitis, is a firm lesion, measuring 1 to 3 cm in diameter, and is most commonly attached to the tendons of the fingers, hands, and wrists, with a predilection for the flexor surfaces. Giant-cell tumor of tendon sheaths most often affect the wrist and fingers of males and females from the ages of 20-50 . These tumors are typically painless and can cause cortical erosion. Surgery to remove the tumor is a common treatment, though the tumors tend to recur.

Gray matter heterotopia (singular "heterotopion") is a neurological disorder caused by clumps of grey matter (ectopic nodules of neurons) located in the wrong part of the brain. It is characterized as a type of cortical dysplasia. The neurons in heterotopia appear to be normal, except for their mislocation; nuclear studies have shown glucose metabolism equal to that of normally positioned gray matter. The condition causes a variety of symptoms, but usually includes some degree of epilepsy or recurring seizures, and often affects the brain's ability to function on higher levels. Symptoms range from nonexistent to profound; the condition is occasionally discovered by brain imaging performed for an unrelated problem and has no apparent ill effect on the patient. At the other extreme, heterotopia can result in severe seizure disorder, loss of motor skills, and mental retardation. Fatalities are practically unknown, other than the death of unborn male fetuses with a specific genetic defect.

Colpocephaly is characterized by disproportionately large occipital horns of the lateral ventricles (also frontal and temporal ventricles in some cases). MRI and CT scans of patients demonstrate abnormally thick gray matter with thin poorly myelinated white matter. This happens as a result of partial or complete absence of the corpus callosum. Corpus callosum is the band of white matter connecting the two cerebral hemispheres. The corpus callosum plays an extremely important role in interhemispheric communication, thus lack of or absence of these neural fibers results in a number of disabilities.

The lemon sign on CT scans of patients refers to the shape of the fetal skull when the frontal bones lose their normal convex contour and appear flattened or inwardly scalloped. This gives the skull a shape similar to that of a lemon. The sign is seen on transverse sonograms of the fetal cranium obtained at the level of the ventricles.

A special case is found in literature where lissencephaly, colpocephaly, and septal agenesis are all present together. The CT scans of the patient shows the ventricular system having a unique appearance of a crown of a king. This is referred to as the 'CROWN SIGN'.

Choristomas, forms of heterotopia, are closely related benign tumors, found in abnormal locations.

It is different from hamartoma. The two can be differentiated as follows: a hamartoma is disorganized overgrowth of tissues in their normal location, (eg, Peutz-Jeghers polyps) while a choristoma is normal tissue growth in an abnormal location (e.g., gastric tissue located in distal ileum in Meckel diverticulum).

Focal nodular hyperplasia (FNH) is a benign tumor of the liver (hepatic tumor), which is the second most prevalent tumor of the liver (the first is hepatic hemangioma). It is usually asymptomatic, rarely grows or bleeds, and has no malignant potential. This tumour was once often resected because it was difficult to distinguish from hepatic adenoma, but with modern multiphase imaging is usually now diagnosed by strict imaging criteria and not resected.

Trichoblastomas are a cutaneous condition characterized by benign neoplasms of follicular germinative cells. Trichoblastic fibroma is a designation used to characterize small nodular trichoblastomas with conspicuous fibrocytic stroma, sometimes constituting over 50% of the lesion.

Progressive nodular histiocytoma is a cutaneous condition characterized by generalized, discrete yellow papules and nodules with prominent facial involvement.

Ganglioneuroblastoma is a variant of neuroblastoma that is surrounded by ganglion cells.

It can be difficult to diagnose.

Nodular ganglioneuroblastoma can be divided by prognosis.

Atypical tuberous myxedema, also known as Jadassohn–Dosseker syndrome, is thought to represent a pure nodular of lichen myxedematosus.