Mucosal melanoma (MM) is a rare and highly aggressive malignancy arising from melanocytes located within mucosal surfaces. Unlike cutaneous melanoma (CM), MM develops in non-sun-exposed mucosa, frequently harbors KIT or SF3B1 mutations, demonstrates a lower tumor mutational burden, and exhibits reduced responsiveness to immunotherapy. These biological differences distinguish MM from CM and contribute to important differences in staging, prognosis, and management. We describe the case of a 71-year-old male who presented with a newly identified pigmented lesion involving the right inferior gingival mucosa. His medical history included type 2 diabetes mellitus, dyslipidemia, and essential hypertension. Biopsy confirmed malignant MM. Positron emission tomography/computed tomography (PET/CT) demonstrated a 1.3 × 1.2 cm fluorodeoxyglucose-avid lesion (SUV max 9.6) without evidence of mandibular invasion, cervical nodal disease, or distant metastasis. The patient underwent radical excision of the lesion with right selective neck dissection (levels I-III). Histopathologic examination confirmed MM (pT3N1) with positive deep margins and metastatic involvement of two regional lymph nodes. This case highlights the diagnostic and therapeutic challenges of oral MM and emphasizes the importance of recognizing the biological and clinical differences between MM and CM. Routine, thorough intraoral soft-tissue examination and early biopsy of suspicious pigmented oral lesions are essential to facilitate timely diagnosis and management of this aggressive malignancy.

Sarcoidosis is a multisystem granulomatous disease of uncertain etiology that most often involves the lungs and skin, though nearly any organ may be affected. Pulmonary disease typically manifests as bilateral hilar lymphadenopathy with diffuse interstitial infiltrates, whereas cutaneous involvement is reported in about 25%-35% of cases, presenting as erythema nodosum, plaques, nodules, or lupus pernio. Acute onset of extensive pulmonary infiltrates with cutaneous lesions other than erythema nodosum is uncommon and frequently misdirects clinicians toward infectious or malignant causes, particularly in tuberculosis-endemic regions. We describe a 35-year-old previously healthy male who presented with sudden dyspnea, persistent cough, and erythematous plaques and nodules on the extremities. Chest imaging revealed diffuse bilateral infiltrates with mediastinal lymphadenopathy, and laboratory findings showed elevated serum angiotensin-converting enzyme levels. Pulmonary function testing demonstrated a restrictive pattern with impaired diffusion capacity, while bronchoalveolar lavage revealed lymphocytosis with a CD4/CD8 ratio above 3.5. Skin biopsy confirmed noncaseating granulomas, establishing the diagnosis of sarcoidosis with pulmonary and cutaneous involvement. The patient was started on oral corticosteroid therapy with prednisone 60 mg daily, gradually tapered according to clinical response. Within 2 weeks, there was marked improvement in respiratory symptoms and regression of skin lesions, leaving only residual pigmentation. Follow-up lung function and imaging demonstrated near-complete resolution, and steroids were successfully discontinued after 6 months without recurrence. This case highlights the importance of recognizing sarcoidosis in acute pulmonary-cutaneous presentations, where timely diagnosis and corticosteroid therapy can lead to excellent outcomes.

Lentigo simplex is a benign melanocytic lesion commonly arising in childhood. We report a 10-year-old girl with a stable periorbital lentigo simplex treated using a 755-nm picosecond alexandrite laser. The patient underwent five treatment sessions over three years, resulting in significant pigment reduction without adverse effects or recurrence. This case highlights the long-term safety and efficacy of picosecond laser treatment for pediatric facial pigmented lesions, particularly in cosmetically sensitive areas. It also adds to the limited literature supporting laser use in children and emphasizes the importance of noninvasive options for aesthetic concerns.

Although estrogen has been identified to play crucial roles in the development of melasma, the exact mechanism of estrogen's effect on pigmentation is incompletely elucidated. Recent studies have highlighted the pivotal role of immune cells in melasma. Interestingly, infiltrated macrophages are significantly enhanced in melasma lesions. Estrogen could facilitate M2 polarization. However, whether estrogen could stimulate melanogenesis via skewing M2 phenotype remains unknown. This study attempted to determine the significance and molecular mechanism of estrogen-induced M2 phenotype in melasma. We found that M2 infiltration was significantly increased in melasma lesions compared with perilesional skin. Arginase 1 was identified as the hub gene, and its expression was positively correlated with that of microphthalmia-associated transcription factor and tyrosinase-related protein 1 in melasma through transcriptome analysis. Moreover, β-estradiol (E2) was confirmed to promote M2 skewing while inhibiting M1 polarization via activating STAT6 signaling. Importantly, E2-induced M2 polarization robustly increased melanogenesis by increasing tyrosinase activity and expression of microphthalmia-associated transcription factor and tyrosinase in melanocytes, which were profoundly inhibited by VEGF knockdown or antagonism both in vitro and in ex vivo skin. Furthermore, VEGF was revealed to enhance melanogenesis through activating p38 MAPK and ERK1/2 signaling pathways in melanocytes. Additionally, dermal VEGF was significantly increased, and most of it colocalized with M2 macrophages in melasma lesions. Crucially, E2 administration potently reversed ovariectomy-decreased M2 skewing and subsequently promoted dermal VEGF expression and epidermal melanogenesis in the mouse tail skin, which were significantly suppressed by macrophage depletion. These findings suggest that estrogen may stimulate melanogenesis in melasma through increasing M2 skewing and VEGF expression and secretion in macrophages.

Melanoma incidence is steadily on the rise but widespread prevention awareness and novel treatment approaches have substantially ameliorated the prognosis of the disease. Microphthalmia-associated transcription factor (MITF) is an essential transcription factor that plays a central role in the transcriptional circuitry of both normal melanocytes and malignant melanoma. Since over 30 years have elapsed since its discovery in mice, a large number of its target genes have been identified in pigment cells. Many upstream regulators of MITF have also been identified. Despite these substantial discoveries, MITF function, especially in melanomas, still remains elusive in several aspects. MITF is absolutely required for melanin formation because it transcribes virtually all genes required for the synthesis, storage, and transport of the pigment. Importantly, MITF is necessary for prevention of apoptosis in melanomas, at least at the early stages. However, in some metastases, MITF may be absent in most cells and its antiapoptotic function is evidently replaced by other proteins that not yet been fully identified. Furthermore, MITF is a specific nevus and melanoma marker, which is routinely used in immunohistochemistry, along with other markers, to distinguish pigmented and other skin lesions. In melanomas, high-MITF melanoma cell subpopulations are considered differentiated, i.e., pigmented and rapidly proliferating. In contrast, low-MITF cells proliferate slowly but are invasive with cancer stem cell-like properties. Although MITF activates mostly antiapoptotic and pro-proliferative genes, it also activates typical cell cycle inhibitors such as the p16 and p21 proteins. Here we discuss the issues of MITF multifunctionality in melanoma and associated research prospects.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder resulting from mutations in nucleotide excision repair. It is characterised by severe photosensitivity, cutaneous pigment changes, malignant tumour development, and occasionally progressive neurologic degeneration. The aim is to report three cases of XP with cutaneous malignancies with emphasis on the importance of prevention of malignant transformation in these patients. Three adults within their 3rd and 4th decades with XP were managed for cutaneous malignancies: two males and one female, two of whom were siblings. Two had fungating lesions on the forehead, and one had multiple scalp lesions. The histology in all the three patients revealed squamous cell carcinoma (SCC). All underwent wide local excision, followed by full and split thickness skin grafting to cover the defects, except the one that had transposition flap at a second surgery, and were co-managed with a dermatologist. Skin malignancies especially SCC and basal cell carcinoma are common in the facial regions of patients with XP. Adequate education of the patients on the importance of protection from the ultraviolet radiation radiations will prevent malignant transformation, and early presentation with appropriate treatment will improve prognosis.

Congenital melanocytic nevi are uncommon benign lesions that primarily involve the skin and are exceedingly rare within the oral cavity, where their atypical presentation may pose a diagnostic challenge due to clinical overlap with other pigmented lesions. We report a case of an intramucosal palatal congenital melanocytic nevus (CMN) in a 34-year-old woman who presented with a painless nodular lesion arising from a lifelong pigmented area of the palate. Histopathological examination demonstrated a benign proliferation of nevus cells with theques formation. The deepest nevus cells showed proximity to the adjacent minor salivary gland lobules. The lesion was managed by complete surgical excision, with uneventful healing at 6-month follow-up. A comprehensive review of the literature identified only 11 reported cases of intraoral CMNs, confirming the palate as the most frequently involved site and a marked female predominance. This case highlights the critical role of correlating clinical history with histopathological findings to achieve an accurate diagnosis.

This paper reports an outbreak of Chamaecrista serpens var. serpens poisoning in Mangalarga Marchador horses, Pega donkeys, Nelore cattle, and Mambrina goats. The disease occurred in the municipality of Iaçu, in the semi-arid region of the state of Bahia, 15-30 days after the start of the rainy season, coinciding with the regrowth of the plant. The prevalence of the poisoning was 100% in donkeys and horses, 11.9% in cattle, and 38.8% in goats. Clinical signs were characterized by itching, edema, and crust formation, predominantly in areas of non-pigmented skin or with less hair coverage and in regions of light-colored skin and hair. Animals of different species sought shade; a characteristic particularly noticeable in horses. Two horses died, possibly as a result of the severity of the lesions. The plant's high availability and palatability contributed to the high prevalence of poisoning. Affected animals recovered 21-28 days after being removed from the areas invaded by the plant and placed in areas with available shade. The results indicate that different species of production animals are susceptible to C. serpens var. serpens poisoning, that C. serpens var. serpens causes significant economic damage to livestock farming in the region, and that it is necessary to develop appropriate technologies to control this invasive plant.