Oral melanoacanthoma: Clinicopathological and immunohistochemical features of a case series and a scoping review.

BACKGROUND: This study presents a case series and scoping review of oral melanoacanthoma to examine its clinical, histopathological, and immunohistochemical characteristics. METHODS: Nine cases of oral melanoacanthoma were included in the case series. Clinical data were collected from biopsy charts. Hematoxylin-eosin and immunohistochemistry for TRP2, CD3, and CD20 were done. For the scoping review, MEDLINE/PubMed, Web of Science, EMBASE, and Scopus were searched. RESULTS: Case series: The mean age was 46.8 years (female-to-male ratio 2:1). Lesion's mean size was 11.0 mm (±9.3). Lesions were mainly macular (77.8%) with brown or black coloration (88.9%) and often affected multiple sites (44.4%). The evolution time ranged from 15 days to 96 months. Lesions commonly showed epithelial acanthosis (66.7%), spongiosis (55.6%), exocytosis (77.8%), melanin incontinence (88.9%), and inflammatory infiltrate in the lamina propria (77.8%), from which all showed lymphocytes. TRP2-positive melanocytes were identified in the basal and spinous layer of all cases, and in the superficial layer of three cases. CD3-positive cells predominate over the CD20-positive. Scoping review: 85 cases of oral melanoacanthoma were retrieved from 55 studies. Patients were primarily female (female-to-male ratio 2.2:1), black-skinned (64.1%), with a mean age of 36.13 (± 17.24). Lesions were flat (81.9%), often brown (62.4%). Buccal mucosa was the preferred site (32.9%), followed by multiple sites (28.2%). CONCLUSION: Oral melanoacanthoma mainly affects women across a wide age range, with lesions commonly appearing as brown/black macules, particularly on the buccal mucosa. TRP2-positive melanocytes and T-lymphocytes were consistently found and could participate in oral melanoacanthoma pathogenesis.

Melanoacanthoma, Plasma Cell Cheilitis and Langerhans Cell Hyperplasia on the Lower Lip: An Unusual Association and Immunohistochemical Analysis.

Oral melanoacanthoma is an uncommon reactive lesion, characterized by basal and prickle cell keratinocyte proliferation surrounded by pigment-laden dendritic melanocytes. Plasma cell cheilitis (PCC) is an inflammatory disorder of unknown aetiology, microscopically presenting a dense plasma cell infiltrate. Most PCC cases affect the lower lip. Langerhans cell hyperplasia (LCHyp), a non-neoplastic counterpart of the LC proliferations, has been reported in association with chronic inflammatory skin diseases. Here, we present an unusual association of melanoacanthoma, PCC and LCHyp on the lower lip in a 59-old-year male, expanding the clinicopathological spectrum of these uncommon lesions. The dendritic melanocytes were highlighted by Fontana-Masson stain and HMB-45, whereas S100, CD1a and CD207 evidenced numerous LCs. MUM1/IRF4, EMA, and CD138 highlighted sheets of polyclonal plasma cells, with an IgG4+/IgG+ ratio of 24%. FTA-ABS test for syphilis was negative.

Melanocitoma-acantoma em um cão / Melanocytoma-acanthoma in a dog

Background: Melanocytic neoplasms are skin tumors that often occur in dogs. However, melanocytoma-acanthoma, alsocalled melanoacanthoma, is a benign melanocytic neoplasm rarely reported in this species, which has been described onlythree times in the veterinary literature. Briefly, this tumor is characterized by a single, painless, darkly pigmented and firmcutaneous papule or nodule. Histologically, it is composed of mixed populations of well-differentiated melanocytes andkeratinocytes, unlike traditional melanocytic tumors (melanoma and melanocytoma). These cells are arranged in lobulessurrounded by collagenous stroma. Melanocytes are large epithelioid cells containing varying amounts of melanin. Keratinocytes form anastomosing trabeculae with peripheral palisading, and small cysts containing amorphous or laminatedkeratin. The definitive diagnosis of melanocytoma-acanthoma is based on histopathological findings. This report describesa case of melanocytoma-acanthoma in a dog in Brazil.Case: A 9-year-old female miniature Schnauzer dog was examined at the Veterinary Hospital of the Federal Universityof Santa Maria, where a single, firm, pigmented papule was found in the auricle. The lesion had started 15 days earlier.Hematological tests and serum biochemistry profile were normal. An excisional biopsy of the papule was surgically removed and subjected to histopathological examination. The tissue was fixed in 10% neutral buffered formalin, processedroutinely and embedded in paraffin wax. Sections were stained with hematoxylin and eosin (HE). A histopathologicalexamination revealed a nonencapsulated, well-defined, extensive, densely cellular proliferation located in dermis. Thisproliferation was composed of lobules and nests of well-differentiated stratified squamous epithelium closely associatedwith neoplastic melanocytes, surrounded by thin bundles of fibrous stroma. A diagnosis of...(AU)

Melanocitoma-acantoma em um cão / Melanocytoma-acanthoma in a dog

Background: Melanocytic neoplasms are skin tumors that often occur in dogs. However, melanocytoma-acanthoma, alsocalled melanoacanthoma, is a benign melanocytic neoplasm rarely reported in this species, which has been described onlythree times in the veterinary literature. Briefly, this tumor is characterized by a single, painless, darkly pigmented and firmcutaneous papule or nodule. Histologically, it is composed of mixed populations of well-differentiated melanocytes andkeratinocytes, unlike traditional melanocytic tumors (melanoma and melanocytoma). These cells are arranged in lobulessurrounded by collagenous stroma. Melanocytes are large epithelioid cells containing varying amounts of melanin. Keratinocytes form anastomosing trabeculae with peripheral palisading, and small cysts containing amorphous or laminatedkeratin. The definitive diagnosis of melanocytoma-acanthoma is based on histopathological findings. This report describesa case of melanocytoma-acanthoma in a dog in Brazil.Case: A 9-year-old female miniature Schnauzer dog was examined at the Veterinary Hospital of the Federal Universityof Santa Maria, where a single, firm, pigmented papule was found in the auricle. The lesion had started 15 days earlier.Hematological tests and serum biochemistry profile were normal. An excisional biopsy of the papule was surgically removed and subjected to histopathological examination. The tissue was fixed in 10% neutral buffered formalin, processedroutinely and embedded in paraffin wax. Sections were stained with hematoxylin and eosin (HE). A histopathologicalexamination revealed a nonencapsulated, well-defined, extensive, densely cellular proliferation located in dermis. Thisproliferation was composed of lobules and nests of well-differentiated stratified squamous epithelium closely associatedwith neoplastic melanocytes, surrounded by thin bundles of fibrous stroma. A diagnosis of...