Nevoid Cells Research Articles

Perineuriomatous nevi: A series of eight cases highlighting unifying pathologic features to avoid misdiagnosis.

Perineuriomatous nevi are rare and diagnostically problematic. We report a series of eight perineuriomatous nevi to highlight the diagnostic features. Cases were retrospectively reviewed and characterized. Median age was 42.5 years (range 25-64), with equal sex distribution. Lesions occurred on the arm (n=4), trunk (n=2), and head/neck (n=2). Median size was 7.5 mm (range 5-12 mm). Clinical differential diagnoses included atypical nevus (3), blue nevus (1), neurofibroma (1), and dermatofibroma (1). Lesions were circumscribed, dome-shaped (5/8), and biphasic (8/8) with nested epithelioid cells and wavy spindled cells arranged in whorled fascicles in a myxocollagenous stroma. When present, junctional growth was lentiginous (4/8). No cases displayed pleomorphism or mitotic figures. The perineuriomatous component stained positively for epithelial membrane antigen (8/8 focal to diffuse) and CD34 (4/5 focal to diffuse). SOX10 and S100 protein stained all nevoid cells and in some cases a subset of intermingled spindled cells in perineuriomatous areas, where other melanocytic markers were negative. p16 protein expression was uniformly retained (3/3), and p53 negative (0/2). Nevoid cells in most lesions were positive for BRAFV600E (5/7). Ki67 was mildly elevated (~5%) in 3/3 cases. Recognizing the histopathologic and immunophenotypic features in these unusual nevi helps avoid overdiagnosis.

RARE CASE OF AN INTRAORAL COMBINED NEVUS

A 13-year-old female patient was referred by her dentist for evaluation of a 5-mm, asymptomatic, black macule in the right buccal mucosa. The patient was unaware of the lesion, and her medical history was noncontributory. A clinical diagnosis of oral melanocytic nevus was made, and the patient was treated by excisional biopsy under local anesthesia. The histologic analysis revealed a proliferation of nevoid cells, organized in small groups and composed of large epithelioid cells with eosinophilic, clear, or dark-brown cytoplasmic melanin granules presenting loose chromatin, prominent nucleoli, and nuclear pleomorphism. In the deeper areas, fusiform nevoid cells presenting dark nuclei with condensed chromatin and dark brown-pigmented cytoplasm were seen intermingled with dense connective tissue. Mitoses were not detected. Based on the findings, a diagnosis of intramucosal combined nevus composed of Spitz and blue nevus was made. No signs of recurrence were observed after 19 months of follow-up. A 13-year-old female patient was referred by her dentist for evaluation of a 5-mm, asymptomatic, black macule in the right buccal mucosa. The patient was unaware of the lesion, and her medical history was noncontributory. A clinical diagnosis of oral melanocytic nevus was made, and the patient was treated by excisional biopsy under local anesthesia. The histologic analysis revealed a proliferation of nevoid cells, organized in small groups and composed of large epithelioid cells with eosinophilic, clear, or dark-brown cytoplasmic melanin granules presenting loose chromatin, prominent nucleoli, and nuclear pleomorphism. In the deeper areas, fusiform nevoid cells presenting dark nuclei with condensed chromatin and dark brown-pigmented cytoplasm were seen intermingled with dense connective tissue. Mitoses were not detected. Based on the findings, a diagnosis of intramucosal combined nevus composed of Spitz and blue nevus was made. No signs of recurrence were observed after 19 months of follow-up.

Giant Congenital Melanocytic Nevus with Proliferative Nodules Mimicking a Congenital Malignant Melanoma

Dear Editor: The malignant transformation of a giant congenital nevus (GCN) is extremely rare, and when it is discovered, the transformation may have already occurred during childhood. Benign proliferative nodules (PNs) in GCN may clinically and histologically mimic a malignant (MM), but clinically, PNs usually present at birth with multiple nodules, which is in contrast to MMs, and histologically, most patients with PNs do not present with the characteristics that are associated with malignancy, including mitotic activity, nuclear pleomorphism, and pagetoid spreading. Furthermore, even though some cases might display these features, they soon disappear1. A one-day-old female child presented with GCN on her lower abdomen, genitalia, anus, and legs. Prenatal ultrasonography revealed an imperforate anus, but no genital abnormalities. Dark brown plaques and some PNs that covered the involved areas were seen during a physical examination (Fig. 1). Satellite nevi were encountered on her scalp, axillae, and ankles. A diagnostic biopsy on a PN was performed, and the histological examination presented a proliferative dermal nodule in a GCN (Fig. 2A). The nevus cells had formed nests in the dermo-epidermal junction and the upper dermis (Fig. 2A, B). They were homogenous without nuclear atypia, pleomorphisms, mitoses, or pagetoid spreading into the epidermis. The melanocytic cells in the dermal nodule showed more dense cellularity than in the background lesion (Fig. 2C), and these cells were more pigmented and larger, and most of them were epithelioid cells that showed little pleomorphism and low-grade cytologic atypia. The features of necrosis were not found. All of these histological features was consistent with a benign PN within a GCN. Immunohistochemical analysis showed that the PN was positive for HMB45 (Fig. 2D), Melan A (Fig. 2E), and SOX-10 (Fig. 2F), which detect melanocytic tumors and Ki-67 protein of less than 2% (Fig. 2G). The patient was transferred to the plastic surgery department and she underwent a staged excision. Fig. 1 A giant congenital nevus with proliferative nodules on lower abdomen, genitalia, anus and lower legs. Fig. 2 (A) Histopathology of the proliferative nodule showed a proliferative dermal nodule in a giant congenital nevus (H&E, ×40). (B) Congenital nevus cells formed nests at the dermo-epidermal junction and upper dermis (H&E, ×200). ... Congenital nevi occur in 1% of newborn infants. Some authors have stated that GCN can be distinguished histologically from acquired nevi by the presence of nevoid cells in the lower two-thirds of the dermis1. Other authors have reported that the nevus cells subsequently migrate deeper into the dermis2. GCN has a 2%~42% risk of malignant transformation, and is associated with a 6%~14% lifetime risk of developing melanoma3. True congenital melanomas are very rare and they are supposed to develop secondary to the transplacental spread of maternal melanomas, arise de novo in uterus, present as prenatal growths on congenital nevi, or arise from neurocutaneous melanosis. A PN within a congenital nevus is also uncommon. Compared with congenital nevus cells, PN cells are larger and more pigmented, they have large nucleoli and a storiform pattern, and they can form nests. These cells have been called melanoma stimulant cells4. The etiology of them is unknown, and they may be a monoclonal proliferation of melanocytic cells. PNs within GCN grow rapidly, show satellitosis5, and they often bring up diagnostic difficulty. In a study of the cells in PNs in GCN, the cells showed high malignancy, but they did not present the typical antigens expressed in MMs, and their subsequent behavior was benign5. But, because the possibility of malignant transformation of this cells is unclear, surgical procedure is recommended to exclude congenital melanoma. We presented the current case to underline the development of benign PN within GCN and to suggest its differential diagnosis from congenital MM.

Case report of giant congenital melanocytic naevus

This is a case of giant congenital melanocytic nevus, associated with a single lipoma & multiple satellite lesions. Biopsy report showed skin with groups of nevoid cells extending into underlying fat, intimately associated with the lobules & surrounding many blood vessels. The systemic examination was normal. This is a typical case of a giant congenital melanocytic nevus with satellite lesions and a lipoma association. As the surface area is greater than 40cm in diameter; the risk of developing melanoma is higher.

Exogenous Trauma Simulating Perifollicular Fibromas

The patient is a 63-year-old woman who presented to her dermatologist for the removal of two nevi near her mouth. Histologic examination revealed melanocytic nevi showing maturation with dermal descent. Within the dermis, adjacent to these nevoid cells, were multiple large hair follicles that were surrounded by dense fibrosis. The fibrous sheaths contained thickened, dense collagen bundles and were well circumscribed, resembling perifollicular fibromas. Further discussion with the patient and the dermatologist revealed that the patient had "plucked" hair from these nevi. We, therefore, believe that the perifollicular fibrosis that we observed is secondary to trauma. We present this case to remind all that post-traumatic events can simulate perifollicular fibromas and that the erroneous diagnosis of such could lead to the erroneous diagnosis of Birt-Hoggs Dubé syndrome.

Compound melanocytic nevi with granular cell changes

Two cases of compound melanocytic nevi with granular cell changes were studied. Histological examination revealed compound melanocytic nevi with a portion of the dermal component exhibiting a sheet like proliferation of nevoid cells with granular cytoplasm. Immunohistochemically, both populations of cells stained positive for S-100 and Melan-A. However, HMB-45 was positive only for the nevus cells with granular cytoplasm. We believe this represents granular cytoplasmic changes of nevus cells and does not denote malignant transformation.

１４歳女子の足縁に生じた黒色結節

Malignant melanoma in childhood is very rare and is often misdiagnosed as Spitz nevus because of their histological similarities. Our patient was 14-year-old girl who had enlarging, raised, pigmented nodule on her left foot. Histopathologically, it showed some features of Spitz nevus. The tumor cells were composed of atypical, pleomorphic epithelioid cells. Mitotic figures were very sparse and small nevoid cells were seen in the deeper potion. But the cyto-fluorometric analysis of nuclear DNA content showed pattern IV, aneuploid pattern. The results of fluorescence microscopy of unstained sections and immunostaining with HMB-45 also suggested the malignant change.

Bilateral Diffuse Iris Nodular Nevi: Clinical and Histopathologic Characterization

Diffuse nodular nevus of the iris is an uncommon condition that presents with multiple verrucous excrescences distributed diffusely on the iris surface. The authors describe 30 patients with bilateral diffuse iris nodular nevi and report associations with bilateral congenital cataract, neurofibromatosis, oculodermal melanocytosis, congenital ptosis, morning glory anomaly, Axenfeld anomaly, or Peters anomaly. Iris nodules were uniform in size and distribution and were brown, as was the surrounding iris. Light and electron microscopy of iridectomy specimens from one patient showed elevated plaques composed of aggregates of plump, lightly pigmented nevoid cells interwoven with mature, densely pigmented spindle-shaped uveal melanocytes. The authors report the largest clinical series and first ultrastructural description of bilateral diffuse iris nodular nevi, which represents a variant of neural crest development. No ocular complications could be attributed to the iris nodules, which should be differentiated from Lisch nodules and other pathologic iris lesions.

Are acquired nevi oestrogen-dependent tumours?

Twelve benign acquired nevi were studied for the possible specific binding of the ER D5 monoclonal antibody. The ER D5 monoclonal antibody identifies the p29 protein, which is found in the cytoplasm of oestrogen-sensitive cells and which is present in a higher concentration than nuclear oestrogen receptors. No staining was seen in nevoid cells, and the results are taken to support the hypothesis that acquired nevi are not oestrogen-dependent tumours.

Patterns of congenital nevocellular nevi: A histologic study of thirty-eight cases

A series of thirty-eight cases of congenital nevocellular nevi were excised and studied histologically. Depending on the extent of nevoid cell dermal infiltration, four histologic patterns were observed: diffuse or patchy infiltration of the upper dermis alone, or diffuse or patchy infiltration of the upper and deep dermis with nevoid cells in or below the lower one third of the reticular dermis. Nevoid cells extended into the deepest reticular dermis in only 37% of these patients. There was no significant correlation between the four histologic patterns and age, sex, location, or lesion size. Two cases recurred after surgery but none underwent malignant change. The patients who developed recurrent nevi in the surgical site postexcision manifested the diffuse upper and deep dermal pattern of nevoid cell infiltration. We interpret this observation as due to incomplete excision of the primary lesion, reflecting the difficulty of removing congenital nevi with this histologic pattern. We conclude from this study that: (1) congenital nevocellular nevi show at least four typical histologic patterns; (2) the nevoid cells of congenital nevi do not necessarily extend into the deep dermis; and (3) of the four histologic patterns seen in congenital nevi, that one showing diffuse and deep placement of nevoid cells on biopsy requires more aggressive excision to prevent recurrence.