Pigmented Neurofibroma Research Articles

Pigmented neurofibroma: A case report of a rare entity

Neurofibromas are benign peripheral nerve sheath tumors seen arising both sporadically and in patients with neurofibromatosis syndromes. Commonly they are of three types: localized, diffuse or plexiform. Pigmented neurofibromas are very rare, accounting to <1% of all neurofibromas reported. We present a case of a 64 year old woman with Neurofibromatosis 1, with a large swelling on the right thigh. The mass was grossly pigmented and microscopically diagnosed as pigmented neurofibroma

Cutaneous Pigmented Neurofibroma in a Pig – Morphology and Immunohistochemical Profile

Peripheral nerve sheath tumours are rare in pigs. In the present case, a juvenile female hybrid pig showed a solitary, pigmented, cutaneous mass. Histologically, it consisted of clustered melanin-laden, epithelioid cells as well as spindle cells forming bundles and nodules. The latter were surrounded by perineurial-like cells. Single Wagner-Meissner-like corpuscles were present. Immunohistochemically, the epithelioid cells expressed S100 protein, melan A and the p75 neurotrophin receptor (p75NTR). The spindle cells expressed S100, sex determining region Y-box 2, p75NTR, Krox20, growth associated protein 43 and glial fibrillary acidic protein. Perineurial-like cells were positive for p75NTR, α-smooth muscle actin and cytokeratin. Taken together, the histological und immunohistochemical findings support the diagnosis of a cutaneous pigmented neurofibroma.

Rectal carcinoma and multiple gastrointestinal stromal tumors (GIST) of the small intestine in a patient with neurofibromatosis type 1: a case report

BackgroundNeurofibromatosis type 1 (NF1) is an autosomally dominant inherited disorder characterized by multiple pigmented skin spots (café-au-lait spots) and neurofibroma. NF1 is associated with a wide variety of benign or malignant tumors. We report a NF1 patient who received surgical treatment for rectal carcinoma and multifocal small intestinal gastrointestinal stromal tumors (GISTs).Case presentationA 70-year-old female patient with NF1 was referred to our hospital after a positive fecal occult blood test. Locally advanced rectal carcinoma was detected in the upper rectum using colonoscopy. A submucosal tumor 20 mm in diameter was detected in the duodenal bulb during the upper gastrointestinal endoscopy. The biopsy specimen from the duodenum was GIST with positive immunostaining of KIT and CD34 microscopically. Laparoscopic low anterior resection for rectal carcinoma and local excision of the duodenal GIST were performed successfully. During the operation, five white small nodules were found on the serosa of the jejunum. One nodule was excised for histological examination. The resected rectal tumor was a well-differentiated adenocarcinoma with multiple lymph nodes metastases according to the histology. The duodenal tumor was found to be low-risk GIST. Moreover, the nodule from the jejunum was very low risk GIST. An excised skin wart was neurofibroma according to the histology.ConclusionsGIST or carcinomas have been reported to occasionally occur in the digestive tract of the patients with NF1. We present a rare case of a NF1 patient with GISTs and colorectal carcinoma.

Melanotic Neurofibroma: A Case Report

Introduction: Melanotic neurofibromas are rare tumours, derived from peripheral nerve sheath, whose originality consists in the presence of melanic pigment. The clinical and histological diagnosis is often difficult to make requiring the immunohistochemical exam to make the difference between melanotic neurofibroma and the other pigmented tumors. Melanotic neurofibroma has a good prognosis and the malignization is rare. Case Report: A 22 year-old man presented since childhood a left occipital tumor, it had a firm consistency and pigmented color. CT objectified isodense occipital mass, which enhanced heterogeneously after contrast product. Lack of bone loss beside. Complete surgical excision was performed. Histological and immunohistochemical analysis led to the diagnosis of melanotic neurofibroma. Discussion: Pigmented neurofibroma is a rare variant of neurofibroma showing melanin production and constitute less than 1% of all cases. It can occur on their own or be associated with neurofibromatosis. They must be distinguished from classical neurofibromas when pigmentation occurs in the latter. Melanotic neurofibromas usually appear in the second or third decade of life and rarely in childhood. The clinical diagnosis is difficult to establish requiring the histopathological examination to differentiate between the melanotic neurofibroma and other pigmented tumours. It can mimicking a giant naevus or a neurocristic cutaneous hamartoma. These are the two main differential diagnoses among children. Among adults, the main difficulty is to distinguish melanotic neurofibroma from pigmented dermatofibrosarcoma. The elective treatment is surgical, represented by the complete excision of the tumor. Conclusion: Pigmented neurofibroma is a unique subtype of neurofibroma which is rare and contains melanin producing cells. The histopathological features with unique pattern of melanogenesis, ultrastructural findings and immunohistochemistry will enable us to diagnose this entity and differentiate it from other pigmented tumours of skin.

Neurotized congenital melanocytic nevus resembling a pigmented neurofibroma.

Neurotized congenital melanocytic nevus and pigmented neurofibroma (PNF) are close mimics and pose a clinicopathological challenge. We present a case of pigmented hypertrichotic plaque over lumbosacral region and discuss the differential diagnosis and its clinical, histopathological and immunohistochemistry features which may aid in differentiation. We highlight the difficulties faced in differentiating neurotized congenital melanocytic nevus from pigmented neurofibroma.

Pigmented neurofibroma of the skin

Pigmented neurofibroma is a rare variant of neurofibroma commonly associated with neurofibromatosis 1 of diffuse type. Histopathologic examination is essential to differentiate it from other pigmented lesions. We report here a case of pigmented neurofibroma of skin, which was diagnosed after histopathology, histochemistry and immunohistochemistry. We also review the pertinent literature to highlight the differential diagnoses.

Immunohistochemical Characterization of a Cutaneous Pigmented Neurofibroma in a Pig

Immunohistochemical Characterization of a Cutaneous Pigmented Neurofibroma in a Pig

A Case of Pigmented Neurofibroma (Bird & Willis) Appearing Solitary on the Instep

A Case of Pigmented Neurofibroma (Bird & Willis) Appearing Solitary on the Instep

Case of pigmented neurofibroma with hypertrichosis with no association to neurofibromatosis

Pigmented neurofibroma (PNF) is a rare cutaneous tumor that has been observed in patients with or without neurofibromatosis (NF). This tumor is histologically characterized by the coexistence of scattered melanin-laden cells and benign spindle cells with neural differentiations. Hypertrichosis is the excessive growth of hair on non-androgen-dependent areas of the body. It has been reported that hypertrichosis may sometimes overlie a neurofibroma. We highlight a case of PNF with hypertrichosis on a 17-year-old woman with no associated NF. We also discuss the possible underlying pathogenic mechanism of a localized hypertrichosis in PNF patients.

Pigmented neurofibroma: review of Japanese patients with an analysis of melanogenesis demonstrating coexpression of c-met protooncogene and microphthalmia-associated transcription factor

Pigmented neurofibroma (PNF) is a rare variant of neurofibroma showing melanin production. To clarify the clinicopathologic features of PNF and to characterize melanogenesis in PNF, 12 cases of PNF were examined in comparison with schwannoma (SCH, n = 16) and neurofibroma (NF, n = 26). The PNF patients were all Japanese including 7 men and 5 women, and patient age ranged from 11 to 71 years (median, 23.5 years). They showed strong a predisposition for neurofibromatosis type 1. Their tumor size was large, and tumors arose from various sites of skin. Histologically, clusters of epithelioid, dendritic, and spindle melanin-producing cells with faint pigmentation had a tendency to locate in deep dermis and subcutis, which seems to be a characteristic pattern of melanogenesis. There was a transition between melanin-producing cells and Schwann cells. Immunohistochemical examination included known melanogenic markers, microphthalmia-associated transcription factor (MITF), which is a key regulator of melanogenesis, and 2 tyrosine kinase receptors, c-Met and c-Kit, which regulate the development of melanocytes. In PNF, melanin-producing cells were S100 (+), MITF (+), Melan-A (+), tyrosinase (+/-), HMB45 (+/-), c-Met (+), and c-Kit (-). Schwann cells were S100 (+), MITF (-), Melan-A (-), tyrosinase (-), HMB45 (-), c-Met (-), and c-Kit (-), and intermediate spindle cells were S100 (+), MITF (+), Melan-A (+), tyrosinase (-), HMB45 (-), c-Met (+), and c-Kit (-). When compared with SCH and NF, MITF was weakly expressed in a part of tumor cells of SCH, whereas no definite staining was found in NF. c-Met expression was very weak in a scattered manner in SCH (10/15 cases) and NF (10/26 cases). These results suggest that PNF is a unique tumor that shows differentiation toward mature melanin production, but ability of melanin synthesis seems to be impaired. There may be a close relationship between up-regulated MITF and c-Met and the peculiar melanogenic nature of PNF, and both of these are useful diagnostic tools for distinguishing PNFs with less melanin production from NFs.

Pigmented (melanotic) neurofibroma: a clinicopathologic and immunohistochemical analysis of 19 lesions from 17 patients.

Neurofibromas with melanin-laden pigmented cells are rare, accounting for less than 1% of all neurofibromas accessioned to the Soft Tissue Registry of the Armed Forces Institute of Pathology between the years 1970 and 1996. This study analyzes the clinicopathologic features associated with 19 specimens removed from 17 patients. Eleven males and six females, ranging in age from 2 to 61 years (median, 28 years), participated in the study. Nine of 15 patients whose race was provided were black. Eight patients (47%) are known to have neurofibromatosis, and two others (12%) are strongly suspected of having this disorder; two patients have similarly affected family members. Eight patients were noted to have multiple skin tumors, and in each of two cases, two pigmented neurofibromas were available for review. Two patients had hypertrichosis and cutaneous hyperpigmentation resembling a hairy nevus, and one had a café au lait spot directly overlying a pigmented neurofibroma. Tumors ranged in size from 1.7 to 50 cm in greatest dimension and involved the buttock or leg (n = 6), head or neck (n = 8), trunk (n = 2), wrist or hand (n = 2), and an unspecified site (n = 1). The neurofibromas exhibited diffuse (n = 15), combined diffuse and plexiform (n = 2), combined diffuse and intraneural epithelioid (n = 1), and nonspecific (n = 1) growth patterns. The process involved the skin (n = 14), subcutis (n = 18), and/or skeletal muscle (n = 3). Wagner-Meissner-like bodies were identified in 11 tumors, and mitoses (average, less than one mitosis per 10 high-power fields) were present in three lesions. All examples contained scattered pigmented cells with dendritic, tadpole-shaped, spindled or epithelioid morphology. These cells were positive with Fontana-Masson (nine of nine) and Warthin-Starry (pH, 3.2; four of four) stains, and were depigmented with a melanin bleach method (two of two). An iron stain was negative. The tumors had immunoreactivity for S-100 protein (11 of 11), HMB-45 ( 10 of 11), Melan-A (four of four), tyrosinase (four of four), and CD34 (four of four). Although recurrences are documented, none of the tumors are known to have undergone malignant transformation. A pigmented neurofibroma can be confused with a pigmented dermatofibrosarcoma protuberans (Bednár tumor) because the melanin-laden cells of both processes are similar. However, the latter entity exhibits a more extensive storiform growth, has greater immunoreactivity for CD34, and lacks a diffuse proliferation of S-100 protein-positive Schwann cells.

Pigmented storiform neurofibroma.

A case of pigmented storiform neurofibroma is presented. The lesion was present in the right loin of a 35-year-old Japanese woman. Grossly, a round, slightly elevated, approximately 1.5 cm in diameter tumor showed a red-purplish coloration of the central part of the overlying skin without ulceration. The characteristic storiform pattern and scattered melanin-containing cells were the relevant features for histological diagnosis. To our knowledge, our case is the second reported case in Japan. The histogenesis and its relationship with tumors of neural crest origin is briefly discussed.