Epidural hibernoma as a complication of corticosteroid treatment. Case report

Spinal Epidural Lipomatosis: A Comprehensive Review

Purpose of review

This is a comprehensive review regarding the epidemiology, diagnosis, and management of spinal epidural lipomatosis (SEL).

Recent Findings

SEL is a relatively rare condition that has gained scientific relevance over the past few decades. Recent findings include expanding treatment strategies to include minimally invasive surgical techniques.

Summary

SEL is caused by an excess of adipose tissue accumulation localized to the thoracic and lumbar regions of the spine. While the exact pathogenesis is not fully elucidated, the etiology of SEL can be broadly classified based on five commonly associated risk factors; exogenous steroid use, obesity, endogenous steroid hormonal disease, spine surgery, and idiopathic disease. Progression of SEL may lead to neurological deficits, myelopathy, radiculopathy, neurogenic claudication, loss of sensation, difficulty voiding, lower extremity weakness, and rarely cauda equina syndrome. Conservative management is largely patient-specific and aimed at mitigating symptoms that arise from shared risk factors. If more advanced treatment measures are necessary, minimally invasive surgery and open surgical techniques, have proven successful.

Management of idiopathic spinal epidural lipomatosis: a case report and review of the literature

BACKGROUND

Spinal epidural lipomatosis (SEL) is a rare pathologic growth of histologically normal unencapsulated adipose tissue in the epidural space. Although rare, SEL can compress the spinal cord or nerve roots causing myelopathy or radiculopathy. While SEL has been associated with long-term exposure to endogenous or exogenous steroids and obesity, idiopathic forms of SEL are much rarer.

CASE REPORT

In this report, we present the first case of SEL isolated to the cervical region compressing the spinal cord in a healthy, non-obese, preadolescent patient.

CONCLUSION

Idiopathic SEL in the pediatric population is a rare entity. This is the first case of epidural lipomatosis isolated to the cervical region in an adult or child patient. In refractory, symptomatic cases of idiopathic SEL, surgical decompression is often required.

Cellular and functional actions of tofacitinib related to the pathophysiology of hibernoma development

Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis. In the 2-year carcinogenicity study with tofacitinib, increased incidence of hibernoma (a neoplasm of brown adipose tissue [BAT]) was noted in female rats at ≥30 mg/kg/day (≥41x human exposure multiples). Thus, signaling pathways within BAT were investigated by measuring BAT: weight, cell proliferation biomarkers, content of basal and prolactin-induced phosphorylated Signal Transducer and Activator of Transcription (STAT), and uncoupling protein 1 (UCP-1). The relationship between cardiovascular hemodynamics and plasma norepinephrine (NE) levels was also investigated. Tofacitinib administered to female rats at doses of 10, 30, or 75 mg/kg/day for 14 days increased BAT weight at 75 mg/kg/day and cell proliferation at ≥30 mg/kg/day. JAK inhibition, observed as lower pSTAT3 and pSTAT5 in BAT, was noted at ≥10 mg/kg/day, while lower activity of BAT was observed as lower UCP-1 protein at ≥30 mg/kg/day. In cultured brown adipocytes, prolactin-induced increase in pSTAT5 and pSTAT3 were inhibited by tofacitinib in a concentration-dependent manner. Tofacitinib lowered blood pressure, increased heart rate, and resulted in dose-dependent increases in circulating NE. Thus, JAK/STAT inhibition in BAT and sympathetic stimulation are two factors which might contribute to the genesis of hibernomas by tofacitinib in rats.

Development of Hibernomas in Rats Dosed with Phentolamine Mesylate During the 24-Month Carcinogenicity Study

Phentolamine is a reversible competitive α-adrenergic antagonist with similar affinities for α1 and α2 receptors. It has a long history of safe clinical use, and was developed as a potential therapy for male erectile dysfunction because of its capacity to increase the arteriolar blood flow to the corpora cavernosa. Phentolamine mesylate was administered to rats by oral gavage at daily doses of 10, 50, and 150 mg/kg for 24 months. A dose-related increase in mortality, ascribed to an exaggerated pharmacologic effect, was seen at high doses. Systemic exposure as measured by plasma drug concentration increased with dose and duration of dosing and slight drug accumulation occurred, particularly in high-dose males. In the treated groups, 10 males and 1 female were diagnosed with hibernomas, neoplasms of brown adipose tissue, which appeared in the thoracic cavity or retroperitoneal area as circumscribed, tan to reddish-brown lobulated masses. Histologically, the masses were well circumscribed with variably sized lobules defined by a rich capillary network and consisted of closely apposed oval to polygonal cells with large amounts of cytoplasm and a centrally located nucleus. The cytoplasm's appearance varied from multivacuolated to univacuolated to granular eosinophilic. In a few cases, neoplastic emboli were observed in capsular vessels. Ultrastructurally, the neoplastic cells contained numerous mitochondria with transverse parallel cristae that occupied over 60% of the cytoplasm and lipid droplets. This study documents the previously unreported development of hibernomas in rats treated with phentolamine mesylate.

Severity of presentation is associated with time to recovery in spinal epidural lipomatosis

We present a patient with prednisone-induced spinal epidural lipomatosis (SEL) and relatively acute neurologic deterioration followed by rapid recovery after surgical decompression. SEL is a rare disease characterized by hypertrophy of epidural fat, most commonly associated with exogenous steroid use. To our knowledge, an analysis of the dynamics of steroid dose related to time to onset has never been performed, or of patient presentation features with respect to patient outcome. We retrospectively reviewed the literature for English language series and case reports of SEL associated with prednisone use from 1975-2013. Data were compiled for 41 patients regarding the prescribed dose of prednisone and length of treatment, as well as the severity of symptoms on the Ranawat scale, time to onset, time to recovery, and degree of recovery of neurological symptoms. Fisher's exact test and analysis of variance were used for comparing proportions, and p values <0.05 were considered statistically significant. We found that the mean cumulative dose of prednisone trended towards an association with a lack of recovery (p=0.06) and may be related to rate of recovery. Prescribed prednisone dose varied inversely with the time before onset of neurological symptoms, but failed to reach statistical significance. Higher severity of presenting symptoms on the Ranawat scale were found to be associated with a higher likelihood of delayed recovery (p=0.035). Patients with symptoms lower on the Ranawat scale more frequently experienced complete neurologic recovery, though this did not reach significance. The acuity of neurological deterioration was not related to the time to recovery or ultimate degree of recovery. Severity of presentation on the Ranawat scale is associated with rate of recovery and may be related to degree of recovery in SEL patients. Cumulative dose of prednisone may be related to degree and rate of recovery. Prescribed dose of prednisone may be related to time to onset of neurological symptoms. Acuity of neurological deterioration is not related to rate or degree of recovery.

Comparative pathophysiology, toxicology, and human cancer risk assessment of pharmaceutical-induced hibernoma

In humans, hibernoma is a very rare, benign neoplasm of brown adipose tissue (BAT) that typically occurs at subcutaneous locations and is successfully treated by surgical excision. No single cause has been accepted to explain these very rare human tumors. In contrast, spontaneous hibernoma in rats is rare, often malignant, usually occurs in the thoracic or abdominal cavity, and metastases are common. In recent years, there has been an increased incidence of spontaneous hibernomas in rat carcinogenicity studies, but overall the occurrence remains relatively low and highly variable across studies. There have only been four reported examples of pharmaceutical-induced hibernoma in rat carcinogenicity studies. These include phentolamine, an alpha-adrenergic antagonist; varenicline, a nicotine partial agonist; tofacitinib, a Janus kinase (JAK) inhibitor; and hydromorphone, an opiod analgesic. Potential non-genotoxic mechanisms that may contribute to the pathogenesis of BAT activation/proliferation and/or subsequent hibernoma development in rats include: (1) physiological stimuli, (2) sympathetic stimulation, (3) peroxisome proliferator-activated receptor (PPAR) agonism, and/or (4) interference or inhibition of JAK/Signal Transducer and Activator of Transcription (JAK/STAT) signaling. The evaluation of an apparent increase of hibernoma in rats from 2-year carcinogenicity studies of novel pharmaceutical therapeutics and its relevance to human safety risk assessment is complex. One should consider: the genotoxicity of the test article, dose/exposure and safety margins, and pathophysiologic and morphologic differences and similarities of hibernoma between rats and humans. Hibernomas observed to date in carcinogenicity studies of pharmaceutical agents do not appear to be relevant for human risk at therapeutic dosages.

Pediatric cervicomediastinal hibernoma: a case report

Hibernoma is a rare lipomatous tumor of brown fat origin. Though uniformly benign in nature these tumors may cause symptoms secondary to extrinsic compression of neighboring structures. Hibernomas may be found anywhere that normal fetal brown fat may be located but are most commonly located in the thigh. We present a case of a hibernoma presenting as an unusual cervicomediastinal mass in a 6-year-old male. This mass was discovered during a diagnostic chest x-ray for pneumonia and treated by resection. Complete surgical resection is considered curative. Hibernoma should be considered in the differential diagnosis of any lipomatous tumor.

Dorsal epidural spinal lipomatosis

The authors report a case of a thoracic epidural spinal lipomatosis causing severe neurological deficits along the review of pertinent literature. The patient is a 56-year-old woman who presented with acute onset of severe paraparesis; she was investigated with cervical and thoracic MRI and then surgically managed because of an intraspinal mass compressing the cord. The operation consisted in the excision of the mass confirmed to be a fibrolipoma by pathological analysis. The patient attained complete neurological recovery and at 18 months follow-up she reported a generalised well-being. Thoracic lipomas are rare lesions that presenting mostly with back pain; however, in rare instances they may cause progressive and/or abrupt neurological dysfunction. Appropriate imaging can help in the diagnosis and management of such cases.

Corticosteroid-induced spinal epidural lipomatosis in the pediatric age group: report of a new case and updated analysis of the literature

Spinal epidural lipomatosis is a rare complication of chronic corticosteroid treatment. We report a new pediatric case and an analysis of this and 19 pediatric cases identified in the international literature. The youngest of these combined 20 patients was 5 years old when lipomatosis was diagnosed. Lipomatosis manifested after a mean of 1.3 (+/- 1.5) years (SD) (median, 0.8 years; range, 3 weeks - 6.5 years) of corticosteroid treatment. The corticosteroid dose at the time of presentation of the lipomatosis ranged widely, between 5 and 80 mg of prednisone/day. Back pain was the most common presenting symptom. Imaging revealed that lipomatosis almost always involved the thoracic spine, extending into the lumbosacral region in a subset of patients. Predominantly lumbosacral involvement was documented in only two cases. Although a neurological deficit at presentation was documented in about half of the cases, surgical decompression was not performed in the cases reported after 1996. Instead, reducing the corticosteroid dose (sometimes combined with dietary restriction to mobilize fat) sufficed to induce remission. In summary, pediatric spinal epidural lipomatosis remains a potentially serious untoward effect of corticosteroid treatment, which, if recognized in a timely manner, can have a good outcome with conservative treatment.

Spinal epidural lipomatosis: case reports, literature review and meta-analysis

BACKGROUND CONTEXT

Symptomatic spinal epidural lipomatosis (SEL), a rare cause of spinal cord compression, has most often been associated with exogenous steroid use.

PURPOSE

Identify four associations with SEL, correlate the associated groups with level of disease and compare treatment with outcome data in these groups.

STUDY DESIGN/SETTING

Case reports of three patients and analysis of 104 cases from the literature.

PATIENT SAMPLE

Three patients from the senior author's practice.

OUTCOME MEASURES

Not applicable.

METHODS

The authors report three new cases of SEL not associated with steroid use. They review all available English literature and present a table of all 104 reported cases.

RESULTS

The clinical course of three new patients is reported.

CONCLUSIONS

Associated conditions are exogenous steroid use, obesity, endogenous steroid excess, and some remain idiopathic. Although SEL is a rare condition, our review of the literature reveals many more reported cases than previously thought. With increased awareness of this condition and improved imaging techniques, further studies of this disease should be undertaken.

Spinal epidural lipomatosis: a review of its causes and recommendations for treatment

Spinal epidural lipomatosis is most commonly observed in patients receiving long-term exogenous steroid therapy, but can also be seen in patients with endogenous steroid overproduction, obesity, or idiopathic disease. With this condition, there is hypertrophy of the epidural adipose tissue, causing a narrowing of the spinal canal and compression of neural structures. A majority of patients will present with progressive myelopathy, but radicular symptoms are also common. Conservative treatment—weaning from steroids or weight loss—can reverse the hypertrophy of the adipose tissue and relieve the neural compression. If conservative management fails, surgery with decompressive laminectomy is also very successful at improving the patient's neurological symptoms.

Growth of intramedullary lipoma in a renal transplant recipient

BACKGROUND

Administration of glucocorticoids can lead to a variety of complications in addition to deposition of fat leading to cushingoid features. Corticosteroids, either endogenously produced or exogenously administered, are implicated in the growth of lipomas in different anatomic locations including the epidural space in the spinal cord causing cord compression.

METHOD

We report a growth of lipoma in an unusual site in a 28-year-old female renal transplant recipient within 6 weeks of renal transplant surgery.

RESULT

Our patient had an intradural lipoma that had merged with the medulla of the spinal cord making its total excision unfeasible without damaging the spinal cord.

CONCLUSION

Epidural lipomas causing cord compression is documented in patients receiving long-term corticosteroid therapy. This is the first case of intramedullary lipoma of the spinal cord that may be related to steroid use.

Intradural spinal hibernoma: case report

BACKGROUND

Hibernoma is a rare, benign tumor arising from vestigial remnants of brown adipose tissue. It usually affects muscle and subcutaneous tissue and is asymptomatic and slow growing.

METHODS

A review of the worldwide literature contains about 110 cases of hibernomas. However, only two cases (including our case) of hibernoma located in the intradural spine have been reported. We present an extremely rare case of intradural extramedullary spinal hibernoma and summarize the magnetic resonance imaging (MRI) findings of the lesion.

CASE DESCRIPTION

A 35-year-old woman suffered from motor weakness and numbness of the left upper extremity. Cervical spinal MRI revealed an intradural extramedullary mass at C7. She underwent surgery via the posterior approach and the lesion was completely removed. Histopathologic examination showed multivacuolated cells with centrally placed nuclei, and the diagnosis of hibernoma was made.

CONCLUSIONS

Because the CT and MRI findings of hibernoma are almost same as those of other lipomatous tumors, a surgical specimen of this tumor is necessary to establish the correct diagnosis. Early diagnosis and total resection are necessary as some cases showed malignant features or rapid growth. Etiologically, the tumor may have developed by the ectopic growth or migration of adipose tissue.

Spinal epidural lipomatosis. Case report and review of the literature

Spinal epidural lipomatosis (SEL) is a condition in which excess adipose tissue is deposited circumferentially about the spinal cord in the epidural space. It is most frequently seen in patients on chronic glucocorticosteroid therapy for a variety of medical problems. This is a case report of lumbar epidural lipomatosis in a bodybuilder with radiculopathy supposedly induced by anabolic steroid intake.

[Lipomatosis induced by corticosteroid therapy]

Steroid-induced lipomatosis usually presents as a localized hypertrophy of the adipose tissue and seems more common than previously thought. Most patients develop this phenomenon after prolonged administration of moderate to high doses of oral corticosteroids. The localizations are numerous and determine the clinical presentation. Often asymptomatic, they can also be revealed by worrying symptoms usually due to a compressive syndrome. The most frequently reported localizations (spinal epidural, retro-orbital, mediastinal) are also the most clinically apparent. The cessation or reduction of steroid therapy, when medically possible, inconsistently results in the decrease or disappearance of the lipomatosis deposits. Computerized tomography or magnetic resonance imaging are the most helpful diagnostic means. Interestingly, these lipomatoses have rarely been reported in patients with Cushing disease. Their pathophysiology remains poorly elucidated and may imply an inhibition of the brown adipose tissue lipolysis.

Scalp hibernoma: case report and literature review

Hibernomas are uncommon, benign neoplasms derived from the remnants of fetal brown adipose tissue. A review of the world literature revealed 105 cases, with the interscapular location the most common. Typically, hibernomas are asymptomatic and slow-growing. Adequate treatment usually consists of simple excision. We describe the second documented case of a scalp hibernoma.

Extrarenal angiomyolipoma with melanocytic and hibernoma-like features

Angiomyolipoma is a tumor commonly occurring in the kidney, but occasionally found in extrarenal sites. Retroperitoneal angiomyolipoma with unusual features presenting in a 39 year old woman with hypertension is reported in this paper. Tumor fat was inconspicuous, and present largely as hibernoma-like microvesicular lipid. Tumor cells also demonstrated positivity for HMB-45 and S-100 protein, and by electron microscopy showed occasional cytoplasmic striated granules indistinguishable from stage II premelanosomes. However, electron microscopy and immunocytochemistry also confirmed the presence of a substantial myogenous component in the tumor, establishing the diagnosis of angiomyolipoma. The implications of these findings, and the role of immunocytochemistry and electron microscopy in the diagnosis of this tumor are discussed.