Cutaneous lipomatous neurofibroma

Noninvasive treatment of cutaneous neurofibromas (cNFs): Results of a randomized prospective, direct comparison of four methods

BACKGROUND

People with Neurofibromatosis Type 1 (NF1) suffer disfigurement and pain when hundreds to thousands of cutaneous neurofibromas (cNFs) appear and grow throughout life. Surgical removal of cNFs under anesthesia is the only standard therapy, leaving surgical scars.

OBJECTIVE

Effective, minimally-invasive, safe, rapid, tolerable treatment(s) of small cNFs that may prevent tumor progression.

METHODS

Safety, tolerability, and efficacy of 4 different treatments were compared in 309, 2-4 mm cNFs across 19 adults with Fitzpatrick skin types (FST) I-IV: radiofrequency (RF) needle coagulation, 755 nm alexandrite laser with suction, 980 nm diode laser, and intratumoral injection of 10 mg/mL deoxycholate. Regional pain, clinical responses, tumor height and volume (by 3D photography) were assessed before, 3 and 6 months post-treatment. Biopsies were obtained electively at 3 months.

RESULTS

There was no scarring or adverse events > grade 2. Each modality significantly (P < .05) reduced or cleared cNFs, with large variation between tumors and participants. Alexandrite laser and deoxycholate were fast and least painful; 980 nm laser was most painful. Growth of cNFs was not stimulated by treatment(s) based on height and volume values at 3 and 6 months compared to baseline.

LIMITATIONS

Intervention was a single treatment session; dosimetry has not been optimized.

CONCLUSIONS

Small cNFs can be rapidly and safely treated without surgery.

Histopathological Variants of Cutaneous Neurofibroma: A Compendious Review

The first description of histopathological variants of neurofibroma dates back to 1994. Over the years, many individual case reports elucidating unusual histologic features in neurofibroma have been added to the literature, some of which have defined criteria, with the others falling under the roof of benign neural neoplasms. These unusual features, which sometimes may lead to pauses in identifying a common benign tumor such as neurofibroma. Awareness of these variants may help dermatopathologists avoid misinterpretation. Thus, this review aims to summarize all novel and unusual histopathological variants of cutaneous neurofibroma reported to date, in addition to any unusual variants that we encountered in our practice.

Prevalence and clinicopathological characteristics of lipomatous neurofibromas in neurofibromatosis 1: An investigation of 229 cutaneous neurofibromas and a systematic review of the literature

BACKGROUND

Lipomatous neurofibroma (Lnf) is a histopathological variant with adipocytes noted among cells of cutaneous neurofibromas. We aimed to investigate the prevalence and clinicopathological features of Lnfs of neurofibromatosis 1 (NF1)-associated cutaneous neurofibromas and to review the literature systematically. We also evaluated the expression of leptin (a hormone involved in lipid metabolism) in neurofibromas to better understand the pathogenesis of Lnfs.

METHODS

A prospective histologic study was conducted on 229 cutaneous neurofibromas from 85 NF1 individuals. Leptin expression was immunohistochemically evaluated in 111 cutaneous neurofibromas. To systematically review the literature, two authors independently performed literature searches without year restriction.

RESULTS

Forty (17.5%) neurofibromas were lipomatous. Lnfs were significantly larger lesions and associated with females. Eighteen (7.9%) of all neurofibromas had multinucleated floret-like giant cells, and these were associated with Lnfs. All neurofibromas expressed leptin. We systematically reviewed 13 articles. Three large studies investigated Lnfs mainly in sporadic neurofibromas and suggested that 0.3% to 8.0% of tumors (NF1 and sporadic) are Lnfs.

CONCLUSION

In NF1, Lnfs are common, mainly in larger tumors and women. All cutaneous NF1-neurofibromas express leptin. It is unknown if the expression of leptin accounts for the lipomatous variant, but it may have a role in the pathogenesis of cutaneous neurofibroma.

Liponeurofibroma: Clinicopathological features and histogenesis

A neurofibroma is a common cutaneous benign tumor of neural origin. Various histological variants have been reported. Recently, sporadic reports of fatty variants have been reported but their clinicopathological features have not been well studied. The purpose of this study was to examine liponeurofibroma, and to report the distinctive clinicopathological features and histogenesis in comparison with the classic form. A retrospective study was performed on 130 cases. Immunohistochemical staining was performed for S100, factor VIIIa, perilipin and vascular endothelial growth factor. Masson's trichrome stain was also used. Intratumoral adipocytes were examined with transmission electron microscopy. Thirty-two (24.6%) cases were classified as liponeurofibroma on microscopic examination. This variant was more common in patients with neurofibromatosis type 1, older age and female sex. The most prevalent location was the head and neck. Intratumoral fat deposits showed differences in morphology and size compared with subcutaneous fat on light microscopy. Neurofibromatosis type 1 had the highest odds of fatty change in liponeurofibroma. In sporadic cases, fatty change can be caused by senescence, chronic injury, or tissue hypoxia secondary to internal or external stimuli. Further investigation is needed to identify the pathomechanism of fatty change in various cutaneous neoplasms, including neurofibroma.

Adipose-Derived Stromal Cells from Lipomas: Isolation, Characterisation and Review of the Literature

OBJECTIVE

The aim of this study was to characterize adipose-derived stromal cells (ADSCs) from patients diagnosed with multiple symmetric lipomatosis (MSL) in order to obtain potentially new insights into the pathophysiology, pathogenesis and treatment of this disease.

METHODS

Cells from the stromal vascular fraction were analysed by the colony-forming efficiency assay and flow cytometry using standard markers. Moreover, the power of adipogenic plasticity was evaluated. Finally, a literature review was performed from 1982 to 2015 using the US National Institutes of Health's PubMed database.

RESULTS

Three European-descent patients diagnosed with either MSL type I or II could be identified for analysis. The resulting mean colony-forming efficiency assay was 14.3 ± 5%. Flow-cytometric analysis of the ADSCs revealed high levels of CD34 (70 ± 9%), CD45 (37 ± 13%) and CD73 (55.8 ± 14%), whereas low levels of CD31 (16.8 ± 14%) and CD105 (5.8 ± 0.7%) were detected. Furthermore, ADSCs showed a strong adipogenic potential, which is in line with the literature review. The stem cell pool in lipoma shows several alterations in biological activities, such as proliferation, apoptosis and stemness.

CONCLUSIONS

ADSCs from lipoma may be interesting in the application of regenerative medicine. We discuss possible molecular treatment options to regulate their activities at the source of the MSL.

Cutaneous microcystic/reticular schwannoma: a poorly recognized entity

BACKGROUND

Microcystic/ reticular schwannoma is exceptionally rare yet distinctive morphological variant of schwannoma with predilection for visceral sites lacking association with neurofibromatosis.

AIMS

To further delineate clinicopathological features of cutaneous microcystic/reticular schwannoma and to discuss its differential diagnosis.

RESULTS

We analyzed three cutaneous microcystic/reticular schwannomas, occurring in two males and one female (mean age: 37.6 years). The tumors presented as a non-painful slightly raised papule (mean: 0.7 cm) on upper arm (n = 2) and back (n = 1). No recurrences were observed despite marginal excision (mean follow up: 42 months). Histopathologically, a multilobular proliferation was present in the dermis composed of bland tumor cells forming distinctive microcystic, reticular, lace-like or pseudoglandular structures, containing abundant myxoid/mucinous material. By immunohistochemistry, tumor cells lining microcystic structures corresponded to Schwann cells (diffuse S100 positive, variable GFAP positivity). A discontinuous EMA-positive perineurium was present at the periphery of some of the lobules.

CONCLUSION

Cutaneous microcystic/reticular schwannoma expands the spectrum of benign peripheral nerve sheath tumors with reticular morphology encountered in the skin. Other tumors in this group include reticular perineurioma and hybrid tumors with reticular morphology, e.g. reticular perineurioma/schwannoma and reticular perineurioma/neurofibroma.

Lipomatous neurofibromas with giant pigmented lesion

Neurofibroma is the most common benign neural tumour. Among the large number of histopathological variants reported, lipomatous neurofibroma is exceedingly infrequent, and shows the presence of intratumoral adipocytes admixed with spindle cells in the dermis. We present a case of a 37-year-old man with lipomatous neurofibromas associated with a giant garment-like pigmented lesion involving his lower trunk and right thigh.

Cutaneous Angioneurofibroma: A New Histopathological Variant of Neurofibroma

Cutaneous neurofibromas are benign dermal tumors composed of spindle cells in a myxoid stroma containing numerous blood vessels. Here we describe 6 cases of solitary cutaneous neurofibroma showing unusually higher density of blood vessels in the stroma when compared to that of classical neurofibromas. We propose this lesion to be a new histopathological variant of neurofibroma and name it angioneurofibroma.

Multiple neural fibrolipomas with macrodactyly

Neural fibrolipoma is an uncommon tumor-like lesion that involves the upper extremity and usually arises in the median nerve. It is associated with macrodactyly in one-third of the cases. A 3-year-old girl presented with increasing size of fingers of both the hands since birth. Clinical examination revealed macrodactyly of two fingers of the right hand and three fingers of the left. Surgical reduction was performed and microscopy of the biopsy specimen established the diagnosis of neural fibrolipoma. Knowledge of the clinicopathological features is necessary for accurate diagnosis and treatment of this rare entity.

Abundant eosinophil infiltration in a neurofibroma

We report a case of sporadic cutaneous neurofibroma showing diffuse eosinophil infiltration in a 72-year-old woman. The neurofibroma had been on the skin of the left anterior shoulder for approximately 10 years. The presence of mast cells is well known in neurofibroma. However, infiltration of neurofibromas by eosinophils has not yet been documented. We propose that eosinophil infiltration is mediated by the effects of mast cells. We suggest that this is indirect evidence that mast cells in some neurofibromas are not quiescent but active. We also reintroduce the notion that acid-fast stains are a useful method to discriminate between mast cell granules and eosinophil granules.

Pure sclerotic neurofibroma: a neurofibroma mimicking sclerotic fibroma

BACKGROUND

Neurofibroma (NF) is a benign tumor of the nerve sheath. Several variants of NF have been described.

PURPOSE

We report a case of NF with sclerotic changes resembling sclerotic fibroma (SF).

METHODS AND RESULTS

The patient was a 61-year-old man who had an asymptomatic cutaneous lesion on the right scapular region. Physical examination revealed a pedunculated, white-to-pinkish nodule that had a firm consistency, spherical morphology, and smooth surface. Microscopically, the nodule showed a well-circumscribed, nonencapsulated dermal tumor composed of scant cells and thick collagen bundles with prominent clefts. The tumor cells were immunoreactive for vimentin and S100 protein. The patient was diagnosed as having pure sclerotic NF. To our knowledge, only five cases of NF with SF-like pattern have been previously published, and in two this pattern was pure.

CONCLUSION

It is important to recognize this exceptional type of NF because it may be easily confused with SF, as well as with a wide variety of neoplasms or hamartomatous conditions containing similar sclerotic pattern.

Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type I, but not sporadic neurofibromas: a study of 226 cases

BACKGROUND

Neurofibromatosis, type 1, is associated with cutaneous melanin pigmentation, but an association with ordinary melanocytic nevi has not been described.

METHODS

This retrospective case-control study was designed to see if neurofibromas in patients with neurofibromatosis, type 1 (NF-1) differ from sporadic neurofibromas (SN) in their incidence of associated melanocytic nevi and other histologic features. Slides from 114 NF-1 were compared with 112 SN and 300 intradermal melanocytic nevi (IDN).

RESULTS

Small lentiginous melanocytic nevi were identified over 13 NF-1 (11%) but no SN (P=0.0002). Compared with other NF-1, NF-1 with nevi were more frequently associated with melanocytic hyperplasia, giant melanosomes and diffuse neurofibroma (P<0.03). Compared with SN, NF-1 were also more frequently associated with melanocytic hyperplasia, lentigo simplex-like changes, diffuse neurofibroma and plexiform neurofibroma (P<0.001). Sebaceous hyperplasia (14%), dermal elastosis (9%), lipomatous change (8%), epithelial cysts (4%) and keratin granulomas or folliculitis (3%) were not significantly different in prevalence between NF-1, SN and the control group of IDN.

CONCLUSIONS

This study suggests that there is a difference in the potential for melanocytic proliferation in NF-1 compared with SN. NF-1, SN and IDN are associated with a similar range of incidental histologic changes. Ball NJ, Kho GT. Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type 1, but not sporadic neurofibromas. A study of 226 cases.

Cutaneous lipomatous neurofibroma: characterization and frequency

BACKGROUND

There are numerous variants of cutaneous neurofibroma reflecting its manner of growth and histologic composition. Lipomatous neurofibroma is the latest described variant with only eight cases reported.

METHODS

A systematic study based on 320 consecutive specimens diagnosed of cutaneous neurofibroma was carried out. Conventional microscopy, immunohistochemistry, and statistical methods were used to determine the presence of fat cells, their amount, distribution, and frequency.

RESULTS

Intratumoral fat was observed in 22 (6.9%) neurofibromas. All these were dermal neurofibromas. Intraneoplastic fat was divided into two groups: focal and diffuse (regularly interspersed). Eighteen tumors (5.6%) presented adipocytes focally intermingled with the spindle cells. There were four (1.3%) neurofibromas showing spindle cell proliferation with regularly scattered adipocytes. Lipomatous neurofibroma was more frequent located on head and neck than non-lipomatous neurofibroma ( p = 0.04). Neurofibromas without mature adipocytes were more frequently immunoreactive for CD34 compared with tumors showing intratumoral fat ( p = 0.02).

CONCLUSIONS

We suggest that both metaplasia and aberrant adipose differentiation from multipotential cells may result in lipomatous neurofibroma. Focal presence of adipose cells may be attributable to metaplasia as the pathogenic mechanism. The fatty tissue being intrinsic to the tumor structure in its diffuse form, the lesion represents a distinctive tumor of the peripheral nerve sheath.