Mitoses in melanocytic lesions

Kissing nevus is a very rare congenital melanocytic nevus. Here, we describe one case of kissing nevus on the penis. A 15-year boy presented with asymptomatic black to dark brown color patches on his penis. Histopathological findings showed that there were nests and cords of nevus cells in upper dermis. No significant cytologic atypia and mitoses were noted. Immunohistochemical stains revealed a partial positive for HMB-45 only in upper dermis and a stronger positivity for S-100 in almost all nevus cells. We diagnosed the lesion as kissing nevus of penis...

The presence of enlarged epithelioid/spindled nests located deep in the reticular dermis of a biphasic melanocytic neoplasm can mimic melanoma arising in a pre-existing nevus, causing over-interpretation of malignancy. We aimed to define the clinicopathologic significance of epithelioid/spindled nests in melanocytic nevi. Retrospectively using clinical and histologic information, we characterized 121 patients with a single lesion showing epithelioid/spindled melanocytes in the reticular dermis or subcutaneous fat, surrounded by melanophages, sometimes blending in with the adnexa...

The epithelioid variant of schwannoma is rare, and loss of SMARCB1/INI1 expression has been observed in a subset of cases. Our aim was to further define the clinicopathologic features and to evaluate SMARCB1/INI1 deficiency in a large cohort of 65 epithelioid schwannomas diagnosed between 2002 and 2015, which consisted of 32 men and 33 women with median age at diagnosis of 45 years (range, 13 to 75 y). Most tumors arose in the extremities (upper, 20, lower, 15) and trunk (17); 9 were visceral (8 gastrointestinal)...

Blue nevus is a benign melanocytic lesion whose most frequent variants are dendritic (common) blue nevus and cellular blue nevus. Atypical cellular blue nevus presents an intermediate histopathology between the typical and a rare variant of malignant blue nevus/melanoma arising in a cellular blue nevus. An 8-year-old child presented a pigmented lesion in the buttock since birth, but with progressive growth in the last two years. After surgical excision, histopathological examination revealed atypical cellular blue nevus...

BACKGROUND: Meningeal melanomatosis is an extra-axial well-encapsulated malignant tumour with diffuse meningeal growth and dark coloration (due to high melanin contents), while meningeal melanocytoma is the focalized benign variant. Melanocytic lesions may be secondary to melanoma or be histologically benign, however, their diffuse nature makes them impossible to cure. Melanocytosis is a diffuse tumour that can form solitary extra-axial tumours, which invades the parenchyma and presents signs of malignancy with increased mitosis and Ki67, observed in 1 to 6% of immunopathological exams...

BACKGROUND: Accurate diagnosis of melanoma remains histologically challenging. Dermal mitoses support malignancy, but are only occasionally seen in melanomas. As melanomagenesis is thought to begin at the dermal-epidermal junction, we investigated the significance of epidermal melanocytic mitoses (EMM) in a spectrum of lesions with molecular characterization. METHODS: Epidermal mitoses density (EMD) was evaluated in 46 straightforward lesions (24 benign and 22 malignant) and 30 challenging lesions with expert interpretation, fluorescence in situ hybridization and myPath-score characterization (12 favor-benign, 9 favor-malignant and 9 ambiguous)...

Melanocytic nevi are submitted for histological evaluation primarily to exclude a malignant process. Mitotic figures are one of the factors used in this assessment. However, there is a lack of data on mitotic activity in juvenile benign nevi. The authors assessed 114 cases of benign melanocytic nevi in children aged 0-15 (inclusive) years old by counting the mitoses present in 2 sections of hematoxylin and eosin-stained tissue. The authors then calculated the proportion of cases in which mitotic activity was present, and the average number of mitoses per case for each age group to get the mitotic rate...

BACKGROUND: Benign melanocytic nevi (MN) of the anal canal are exceptional and require adequate differential diagnosis. There are no data on incidence of these lesions. Only a single case report of hemorrhoid with an MN has been reported. The necessity of routine pathologic evaluation of hemorrhoidectomy specimens has been questioned. MATERIAL AND METHODS: The authors undertook a retrospective histologic study of the hemorrhoidal tissue obtained in a series of 1918 consecutive hemorrhoidectomies performed between January 2004 and November 2012...

Any mitotic activity in a melanocytic nevus is a source of concern about the biologic potential of that lesion, especially in an adult. Previously diagnosed benign melanocytic nevi in individuals from six different age groups were re-examined; mitotic figures were counted in routine hematoxylin and eosin-stained sections; Ki-67 nuclear positivity was assessed by immunohistochemistry. Mitoses were seen in 0-14.3% of nevi in all groups of patients >1 year of age; 55.6% (5/9 cases) of nevi in patients <1-year old had mitoses identified histologically...

Spitz nevus is a benign melanocytic lesion and also one of the main differential diagnosis of melanoma. A descriptive and retrospective study of surgical specimens from patients with a diagnosis of Spitz nevus was conducted at two institutions in Niterói - RJ. 32 cases were analyzed. The most frequent histological subtype was compound (60 %), with a predominance of epithelioid cells (17 cases - 53%). Pagetoid spread was observed in 21 cases (68%). Maturation of melanocytes was present in 13 cases (81%). Kamino bodies were found in eight cases (25%)...

Differentiating proliferative nodules (PNs) from melanomas arising in congenital nevi (CN) is a considerable challenge for dermatopathologists. Most of the specimens dermatopathologists assess that deal with this differential diagnosis involve proliferations of melanocytes arising in the dermis. In this study, we compare the clinical, histologic, and molecular findings of these 2 conditions. In our database, we found 22 examples of PNs arising in the dermis of CN and 2 cases of lethal melanomas arising from the dermis/epidermis of CN of children...

BACKGROUND: Pigmented epitheliod melanocytoma (PEM) is a uncommon melanocytoma with unique histopathological features and possibly with a favourable prognosis, because, although sentinel lymph-node metastases may occur, in the great majority of cases described up to now there is no spread beyond regional lymph-nodes. The nature of PEM, its biologic behaviour and its relationships to naevi and melanoma, however, remain to be clearly established, and several Authors suggest that further cases of PEM with long follow-up should be published, in order to better assess the biologic/prognostic characteristics of PEM...

Melanocytomas are present in leptomeninges and arise from neural crest during early embryonic development. They are a rare entity and usually occur in the thoracic spine and infratentorial region. We report a 32-year-old female with meningeal melanocytoma of D9-10. Magnetic resonance imaging revealed an intramedullary spinal tumor at D9-D10. Intraoperatively, the tumor was greyish-black in color with moderate vascularity, and was adherent to the cord. The clinical differential diagnoses included cavernoma and melanocytoma...

BACKGROUND: Histiocytoma (HC) is a very common benign tumour generally seen in the lower limbs of adults, particularly women. There are, however, atypical forms of HC that behave like locally aggressive tumours, occasionally with relapse or even metastasis. Herein we report a case of locally aggressive HC in a child, which, on account of its clinical extension, required seven surgical procedures to achieve complete excision. PATIENTS AND METHODS: A 13-year-old child consulted for a hard purplish papule measuring 8 mm in diameter located in the right lumbar region...

Predicting clinical behavior of atypical Spitz tumors remains problematic. In this study, we assessed interobserver agreement of diagnosis by 13 expert dermatopathologists for atypical Spitz tumors (n=75). We determined which histomorphologic features were most heavily weighted for their diagnostic significance by the experts and also which histomorphologic features had a statistically significant correlation with clinical outcome. There was a low interobserver agreement among the experts in categorizing lesions as malignant versus nonmalignant (κ=0...

Perivascular epithelioid cell tumors (PEComas) are distinctive mesenchymal neoplasms that most often arise in the retroperitoneum, visceral organs, and abdominopelvic sites and usually show reactivity for melanocytic and smooth muscle markers. Fewer than 20 PEComas of the gastrointestinal (GI) tract have been reported, and behavior and criteria for malignancy are incompletely defined. The purpose of this study was to examine the clinicopathologic features of a series of GI PEComas and to evaluate prognostic parameters...

Perivascular epithelioid tumors (PEComa) are uncommon mesenchymal neoplasms demonstrating positivity for muscular and melanocytic immuno-markers. Included in this category are angiomyolipoma, lymphangioleiomyomatosis, and clear cell sugar tumors. Lesions which do not fit into these categories are classified as "not otherwise specified". We present a case of an incidentally discovered PEComa within inguinal hernia sac contents in a 70-year-old woman. It consisted of spindled and epithelioid cells with bland oval nuclei, small nucleoli and clear to light eosinophilic cytoplasm...

The blue nevus is a variant of a melanocytic nevus that presents as blue-gray to blue or black papules or nodules measuring up to 1 cm in diameter; it has a predilection for females and can be congenital or acquired. The classification of blue nevi is complex, with biological behavior being benign, borderline, or malignant. The case we present is one of a 40-year-old woman with multiple dermatofibromas that appeared and increased gradually in size during pregnancy. Physical examination revealed three spherical, brownish to red-purple nodules localized on the left leg, right shoulder and right laterocervical area...

BACKGROUND: Melanocytomas of the Central Nervous System (CNS) are rare and benign lesions. These slow-growing tumours can behave aggressively, with local recurrence. Various genetic aberrations occur in malignant melanomas and raise possible new therapeutic options. However, little information is available regarding these characteristic genetic alterations in melanocytomas of the CNS. This study was designed to better understand the clinicopathological and molecular features of melanocytomas...

Spitz nevus is one of the most difficult melanocytic lesions to diagnose in regard of malignancy, even for experienced dermatopathologists. We analyzed 28 tumors with Spitzoid morphology from 15 children (three little children 2-4-year-old, 12 peripubertary children 9-17-year-old) and 13 adults; there were 21 Spitz nevi, five atypical Spitz tumors and two Spitzoid melanomas in order to establish the diagnostic value of several morphologic parameters in different age groups. No significant differences in respect of age and/or tumor type occurred for gender, location, dimension, symmetry, sharp lateral demarcation, junctional nests orientation, adipose tissue extension, side-to-side cytologic symmetry, uniform melanin deposits, nuclear pleomorphism, presence of mitoses, inflammation and epidermal alterations...