Breast hibernomas: Questioning the embryological origin?

This paper aims to review the concept of hibernomas, with focus on their occurrence, in the breast. It will make reference to a specific case from the Helen Joseph Hospital's Breast Clinic situated in Johannesburg, South Africa. We describe the clinical, radiological and pathological findings in a patient as well as the final diagnosis and treatment (in the form of surgery). This report emphasizes the distinguishable features of hibernomas, and gives guidance as to the surgical approach in large hibernomas stressing the ease of achieving cosmesis without major oncoplastic techniques. More specifically, discussion as whether these rapidly growing, nonrecurring, usually encapsulated growths consisting of brown fat tissue similar to that found in hibernating animals arise from the breast or the underlying muscle is considered.

Prenatal diagnosis of pericallosal curvilinear lipoma: specific imaging pattern and diagnostic pitfalls.

We report the first series of cases of pericallosal curvilinear lipoma (CL) diagnosed prenatally and highlight the limitations in identifying a specific prenatal imaging pattern using ultrasound and magnetic resonance imaging (MRI). In all five of our cases, on ultrasound, the main feature leading to referral was a short corpus callosum. This subtle callosal dysgenesis was associated with a band of hyperechogenicity surrounding the corpus callosum, mimicking the pericallosal sulcus, which increased in size during the third trimester in three of the four cases in which sonographic follow-up was performed. On T2-weighted MRI, this band showed typical hypointensity in all cases; in contrast, on T1-weighted imaging, in only one case was there hyperintensity, suggestive of fat, as seen typically in the postnatal period. For appropriate prenatal counseling regarding outcome, it is important to identify or rule out CL when mild corpus callosal dysgenesis is observed. One should be aware of subtle diagnostic findings, such as a thin band of echogenicity surrounding the corpus callosum that is seen as a band of hypointensity on T2-weighted fetal MRI, and which may increase in size during gestation. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Variability of T1-weighted signal intensity of pericallosal lipomas in the fetus.

BACKGROUND: Pericallosal lipomas are often associated with corpus callosum dysgenesis. The diagnosis of lipoma, suggested on ultrasonography, relies on the classic T1 hyperintensity on magnetic resonance imaging (MRI). However, this feature may be absent prenatally. OBJECTIVE: Our objective was to study the changes of T1 intensity in fetal lipomas with comparison to postnatal/postmortem data and to assess the factors influencing the signal variations of pericallosal lipomas on prenatal MRI. MATERIALS AND METHODS: Patients with callosum dysgenesis and interhemispheric hyperechogenicity suggestive of a pericallosal lipoma with available postnatal or postmortem data were included. Gestational age, lipoma size and pattern, corpus callosum size and changes in fetal fat T1 intensity were recorded. Comparison with postmortem neuropathology was available for one fetus. RESULTS: Eleven patients with callosum dysgenesis and pericallosal lipomas (seven curvilinear and four tubulonodular) were included. All MRI scans were performed in the third trimester. Curvilinear lipomas were thinner and six cases were associated with prenatal T1 iso-intensity. Typical T1 hyperintensity appeared on postnatal MRI only. All tubulonodular lipomas were much larger and showed prenatal T1 hyperintensity. In two patients, the lipoma increased in size on postnatal MRI. CONCLUSION: The type and size of a lipoma influence T1 prenatal intensity. Absence of T1 intensity was observed in curvilinear lipomas only. Curvilinear lipomas are much thinner. Changes in T1 intensity may also be related to fat maturation within the lipoma and, subsequently, to gestational age. In the case of callosum dysgenesis, absence of prenatal T1 pericallosal hyperintensity should not exclude the diagnosis of pericallosal lipoma.

Bifid scrotum and anocutaneous fistula associated with a perineal lipomatous tumor complicated by temporary bilateral cryptorchidism in utero mimicking ambiguous genitalia: 2-D/3-D fetal ultrasonography.

Ambiguous genitalia (AG) is a morphological diagnosis defined as genitalia not typical of a male or female. Findings mimicking AG, such as penoscrotal anomalies, anorectal malformations, and perineal lipomatous tumors, may prevent accurate identification of the fetal sex. We report a case of bifid scrotum and anocutaneous fistula associated with a perineal lipomatous tumor complicated by temporary bilateral cryptorchidism in utero, which were findings mimicking AG. Several perineal anomalies are associated developmental occurrences. In the present case, the combination of bifid scrotum and temporary bilateral cryptorchidism in the male fetus mimicked the combination of clitoromegaly and prominent labia, which are commonly observed in female fetuses. However, serial systemic assessments using prenatal 2-D/3-D ultrasonography and magnetic resonance imaging were unable to detect the anocutaneous fistula and differentiate the perineal lipomatous tumor. This case report suggests that the prenatal detection of perineal abnormalities may warn obstetricians of potentially undetected congenital perineal anomalies.

Disgenesia do corpo caloso e lipoma: considerações embriológicas básicas e aspectos de imagem à ressonância magnética / Corpus callosum dysgenesis and lipoma; embriologic and magnetic resonance imaging aspects

O corpo caloso é a maior via de fibras de associação que comunicam os dois hemisférios cerebrais. O aprimoramento no estudo das suas malformações foi alcançado após o advento da ressonância magnética, que permite estudar detalhadamente as suas várias porções, além de possibilitar a identificação de outras anormalidades encefálicas associadas. O lipoma do corpo caloso é uma dessas alterações e representa achado freqüente no espectro das disgenesias do corpo caloso. Os objetivos dos autores são os de recordar o mecanismo embriológico envolvido nas disgenesias do corpo caloso e na formação dos lipomas desta região e revisar os achados à ressonância magnética nestas situações.

Human tail with noncontiguous intraspinal lipoma and spinal cord tethering: case report and embryologic discussion.

Children born with a tail-like appendage have a rare malformation that is frequently associated with abnormalities of the spine and spinal cord. A contiguous fibrolipoma is usually seen extending from the subcutaneous portion of the tail into the inferior spinal cord, resulting in tethered cord syndrome. We present the case of a child born with a tail and intraspinal lipoma that were not contiguous with each other, and were separated by an intact layer of lumbosacral fascia. The tail and lipoma were removed and the spinal cord untethered, and the child is neurologically normal 2 years after surgery. The absence of a contiguous lipoma from the tail to the spinal cord suggests that this condition may be principally caused by a disorder of secondary neurulation and/or regression of the normal embryonic tail bud. The embryology of the lower spine is reviewed and possible etiologies discussed.

Pathogenesis of lumbosacral lipoma: a test of the "premature dysjunction" theory.

Premature separation of the neuroectoderm from the ipsilateral surface ectoderm allowing mesenchymal tissue to invade into the central canal, or "premature dysjunction" theory, was proposed for the pathogenesis of dorsal type lumbosacral lipoma. To test this theory, the unilateral neural fold was incised using Hamburger and Hamilton stage 12 or 13 chick embryos. Among 35 embryos evaluated, 15 showed abnormal findings, and of these one showed findings which suggested lumbosacral lipoma: a back lump, blending of the neuroepithelium and mesenchyme through indistinct basement membrane and vertebral body abnormalities. The other 14 embryos showed abnormalities including blunt tails, open neural tube defects, incomplete closure of the dorsal neuroepithelium with intact skin, skin dimples, disorganized gray matter, scoliosis, ectopic neuroepithelium and an accessory spinal cord. The results revealed that the incision of the unilateral neural fold in the early chick embryo may produce a lesion suggestive of lumbosacral lipoma, a finding which supports the premature dysjunction theory. This method needs further refinement to overcome technical difficulties, high mortality, and a low yield before being adopted as an experimental model for lumbosacral lipoma.

[Lipomatous hamartomas of the brain--malformations of the subarachnoid space]. / Lipomatózní hamartomy mozku--malformace subarachnoidálního prostoru.

Lipomatous hamartomas are rare disorders affecting the central nervous system. In our report, two observations of this disorder are presented. Both are interhemispheric in location and are associated with a complete agenesis of the corpus callosum, while having different histological structures. In our first patient, the intracranial formation caused refractory seizures, was partially surgically removed, and a biopsy was performed. Light microscopic examination disclosed the presence of a highly vascularized mature adipose tissue with numerous calcifications. The second case was an incidental finding at autopsy. Microscopically, we found adipose tissue together with numerous foci of hemopoiesis and structures of lamelar bone. In both cases, the indistinct demarcation of the collagenous capsule from the surrounding brain tissue and the continuity of the hamartoma with the leptomeninges were striking. In recent findings about the development of meninges and brain commissures, the origin of this disorder is explained as a defective resorption of the embryonic meninx primitiva. This disorder then causes other developmental aberrations of the brain, which are often found in association. The varying microscopic pattern of these disorders can also be satisfactorily explained by their origin in the primitive meninx, which is formed from both mesenchyme and neuroectoderm.

Embryogenesis. Why do we need a new explanation for the emergence of spina bifida with lipoma?

Spina bifida with lipoma is a human malformation that most often affects the lumbosacral area. It is a complex morphological type. Its origin is controversial, and none of the previous hypotheses can be retained in view of the most recent advances in experimental embryogenesis. Contrary to earlier opinions, adipocytes cannot arise from meninges, vessels or glial cells and spina bifida cannot be explained by incarceration of mesodermal tissues during primary neurulation or developmental defect at the level of the tail bud. Spina bifida with lipoma, which actually involves all the derivatives of the so-called dorsal mesoderm, must therefore result from abnormal development of this mesoderm, which is induced by the dorsal neural tube. The location of the primary defect (dorsal mesoderm or neural tube) remains to be established.

[Prenatal diagnosis of an intraspinal lipoma. A case report]. / Diagnostic prénatal d'un lipome intra-rachidien. A propos d'un cas.

This report describes a prenatal diagnosis of intraspinal lipoma. This pathology, not well known by obstetricians, forms a part of neural tube defects. Echographic aspect, embryologic origin, differential diagnosis, neurosurgical prognosis and treatment are reviewed and discussed.

Interhemispheric lipoma with variable callosal dysgenesis: relationship between embryology, morphology, and symptomatology.

Eight interhemispheric lipomas (five tubulonodular lipomas and three curvilinear lipomas) were examined by magnetic resonance imaging (MRI). The purpose was to further investigate the relationship between the morphology of the different subtypes and the clinical presentation. The imaging findings were reviewed in light of a recent theory on the development of the corpus callosum. Interhemispheric lipomas should be considered as one entity with a variable expression depending on the severity and/or the time of the insult. Curvilinear lipomas can be either small or extensive and are usually not symptomatic. Tubulonodular lipomas can be either predominantly anterior or posterior in location. The anterior subtype appears to be a more severe form of tubulonodular lipoma. The associated structural abnormalities are most likely responsible for the symptoms, rather than the lipoma itself. Magnetic resonance imaging allows a more precise timing of the insult, resulting in the development of a lipoma. The knowledge of the embryology between the 6th and the 20th week is important to explain these abnormalities. Until now it has been accepted that the corpus callosum develops in an orderly fashion. A recent theory has demonstrated that this is not necessarily true, and that fibers can cross the midline at any place irrespective of the normal development. This theory explains the sometimes amorphous appearance of the remnant of the corpus callosum if a lipoma is present.

[Spinal lipomas in childhood]. / Lipomi spinali in età pediatrica.

Spinal lipomas account for 5% of the tumors of the spinal cord, frequently present already at birth. Most commonly they are associated with forms of dysraphism, but lipomas without bony involvement are considered dysembriogenetic lesions too. Children with lipoma frequently have intact neurological functions, but may become symptomatic later on. Diagnosis is possible also in neurologically intact patients because of skin lesions or subcutaneous masses. Many surgeons suggest early surgery to prevent injury to neural structures from traction due to cord tethering; others prefer to wait for the rise of any symptom before considering surgery. However, neurological recovery after surgery is rarely observed, and, when present, is always partial; the primary goal of surgery is to stop the clinical progression through the detethering of the cord.

Leptomyelolipoma: analysis of 20 cases.

Leptomyelolipoma (lumbosacral lipoma) is a common form of spinal dysraphism. The deficits produced include sensory, motor, bowel, and bladder dysfunction, and vary in incidence between the pediatric and adult populations. Twenty patients treated surgically at the Mount Sinai Hospital between 1972 and 1988 are reviewed. Fifty percent were 12 years of age or less and 50% were older than 18 years of age. The surgical approach was designed to accomplish untethering of the conus medullaris, debulking of the lipomatous mass compressing the cord, reconstruction of the dural canal, and reapproximation of the paraspinal muscles and lumbosacral fascia to prevent future trauma. Postoperatively, no patient experienced deterioration of neurological function. Of the symptomatic patients. 67% displayed dramatic improvement or became asymptomatic and 33% experienced stabilization of their deficits. The symptoms most resistant to surgical correction were orthopedic foot deformities and bowel dysfunction, whereas bladder dysfunction, motor weakness, and radiculopathies were most amenable to surgical therapy. Early surgical repair is recommended in these cases to forestall irreversible neurological damage.

Coelomic fat ectopia in the liver.

We describe a pedunculated, mesothelial-covered liver mass contained in a mesothelial-lined sac. Microscopically, the mass was composed of mature adipose tissue that contained thick-walled arteries and large veins, fibrous tissue, and numerous bundles of smooth muscle. The lesion was thought to represent ectopic coelomic mesenchyme originally destined to form omentum or mesentery. The existence of this entity suggested that previously reported cases of hepatic adipose tissue masses (lipomas) might also have derived from ectopic coelomic mesenchyme. Along with the mesenchymal lesion in the liver, an unclassifiable mesenchymal tumor was present in the cerebellum. Whether the coexistence of the two mesenchymal tissue masses was fortuitous, or related, could not be determined from this solitary case.

[2 cases of thyroid lipoma]. / Deux cas de thyro-lipome.

Report of two cases of thyro-lipoma, a rare variety of adenoma containing fat cells. Only five cases have been reported. Embryogenic or metaplasic origin of the adipose tissue is discussed.