Pulse oximetry is widely used to non-invasively estimate the oxygen saturation of haemoglobin in arterial blood (SpO2). It is used widely throughout healthcare and was used extensively during the Covid-19 pandemic to detect and treat hypoxic patients. Research has suggested that pulse oximetry is less accurate in patients with darker skin. This led the US Food and Drug Administration agency (FDA) to issue a safety statement warning that pulse oximeters may be inaccurate when patients have pigmented skin. Evidence suggests that the oxygen saturation of arterial blood (SaO2) may be being overestimated by measuring SpO2 in those with pigmented skin. The degree of overestimation increases as SaO2 decreases especially when SpO2 reads below 80%. We review how pulse oximetry works and consider the implications for a patient\'s health when interpreting SpO2 in individuals with pigmented skin.

Malignant melanoma is the leading cause of death from skin cancer. In spite of significant advances in the management of melanoma with the advent of sentinel lymph node biopsy (SLNB) and adjuvant oncological therapies, the death rate continues to increase worldwide. Melanoma in the hand poses additional diagnostic and management challenges. Consequently, these tend to present at a later stage and are associated with a poorer prognosis. It is imperative that hand surgeons treat any pigmented hand lesion with suspicion to ensure rapid diagnosis and treatment. This article outlines the presentation of melanoma, and how to investigate suspicious pigmented lesions of the hand and digits. It guides hand surgeons in their approach to melanoma of the hand, outlining the multidisciplinary team approach as well as current standard surgical and reconstructive options to optimize outcomes.

Multiple aggregated yellow-white globules (MAY globules) have been recently described as dermoscopic structures of high specificity associated with high-risk non-pigmented basal cell carcinoma (BCC). To evaluate the diagnostic accuracy of MAY globules in a cohort of pigmented and non-pigmented BCC of all histological types. This was a retrospective case-control study. Dermoscopic and clinical images were all histopathologically confirmed as BCCs of patients seen consecutively at dermatology consultation. Control cases were benign or malignant tumours randomly selected from the database of 8,250 patients. A total of 389 BCCs were included. MAY globules were present in 192 (49%) cases in the BCC group and in only 25 cases in the control group (6,4%). The odds ratio for the diagnosis of BCC was 14.2 (95% CI: 9.62-20.95]). The presence of MAY globules was significant in three histological subtypes, including superficial BCCs. This study shows that MAY globules are a major dermoscopic sign for the diagnosis of BCC, regardless of their histological subtype and their pigmentation.

BACKGROUND: Pigmented fungiform papillae of the tongue (PFPT) is a rare benign pigmentary disorder of the tongue. In dark-skinned individuals, PFPT appears to be relatively common. However, limited data exist on PFPT in Korean patients.
OBJECTIVE: We aimed to investigate the clinical characteristics of PFPT in Korean patients.
METHODS: Patients diagnosed with PFPT between 1995 and 2021 at the Pusan National University Hospital were included. Clinical characteristics of PFPT, dermoscopic findings, and comorbidities were reviewed.
RESULTS: A total of 19 patients diagnosed with PFPT were enrolled. The male to female ratio was approximately 1:5. The mean age at diagnosis was 41.1 years (range, 8~67 years). According to Holzwanger\'s classification, Type I was the most common (89.5%). PFPT was commonly concomitant with pigmentary disorders, including mucosal melanotic macules, Laugier-Hunziker syndrome, melasma, and melanonychia (6/19, 31.6%). Preceding oral infection or inflammatory lesions were found in four patients (21.1%), and systemic diseases and infectious diseases existed in two patients (10.5%). Dermoscopic examination was performed in seven patients; pigmented border with dichotomized vessels (rose petal pattern, 71.4%) and diffuse pigmentation (cobblestone pattern, 71.4%) were common findings.
CONCLUSIONS: Our study shows PFPT can coexist with pigmentary disorders. Concomitant pigmentary disorder shows an association with sex hormone or susceptibility to abnormal pigmentation may be a possible cause of PFPT.

Ependymomas have rarely been described to contain pigment other than melanin, neuromelanin, lipofuscin or a combination. In this case report, we present a pigmented ependymoma in the fourth ventricle of an adult patient and review 16 additional cases of pigmented ependymoma from the literature. A 46-year-old female showed up with hearing loss, headaches, and nausea. Magnetic resonance imaging revealed a 2.5 cm contrast-enhancing cystic mass in the fourth ventricle, which was resected. Intraoperatively, the tumor appeared grey-brown, cystic, and was adherent to the brainstem. Routine histology revealed a tumor with true rosettes, perivascular pseudorosettes and ependymal canals consistent with ependymoma, but also showed chronic inflammation and abundant distended pigmented tumor cells that mimicked macrophages in frozen and permanent sections. The pigmented cells were positive for GFAP and negative for CD163 consonant with glial tumor cells. The pigment was negative for Fontana-Masson, positive for Periodic-acid Schiff and autofluorescent, which coincide with characteristics of lipofuscin. Proliferation indices were low and H3K27me3 showed partial loss. H3K27me 3 is an epigenetic modification to the DNA packaging protein Histone H3 that indicates the tri-methylation of lysine 27 on histone H3 protein. This methylation classification was compatible with a posterior fossa group B ependymoma (EPN_PFB). The patient was clinically well without recurrence at three-month post-operative follow-up appointment. Our analysis of all 17 cases, including the one presented, shows that pigmented ependymomas are most common in the middle-aged with a median age of 42 years and most have a favorable outcome. However, one patient that also developed secondary leptomeningeal melanin accumulations died. Most (58.8%) arise in the 4th ventricle, while spinal cord (17.6%) and supratentorial locations (17.6%) were less common. The age of presentation and generally good prognosis raise the question of whether most other posterior fossa pigmented ependymomas may also fall into the EPN_PFB group, but additional study is required to address that question.

BACKGROUND: A lot of congenital melanocytic nevi (CMN) carry the somatic mutation in the oncogene BRAF V600E. But the detailed histopathologic characteristics and the proliferative activity of CMN with BRAF V600E gene mutation have not been systematically documented.
OBJECTIVE: To identify the proliferative activity and histopathological features correlating them with BRAF V600E gene mutation status in CMN.
METHODS: CMN were retrospectively identified from the laboratory reporting system. Mutations were determined by Sanger sequencing. The CMN were divided into a mutant group and control group according to whether there was BRAF gene mutation and were strictly matched according to gender, age, nevus size, and location. Histopathological analysis, analysis of Ki67 expression by immunohistochemistry and laser confocal fluorescence microscopy were performed.
RESULTS: The differences in Ki67 index, the depth of nevus cell involvement and the number of nevus cell nests between the mutant group and the control group was statistically significant, with p-values of 0.041, 0.002 and 0.007, respectively. Compared with BRAF V600E negative nevi, BRAF V600E positive nevi often exhibited predominantly nested intraepidermal melanocytes, and larger junctional nests, but the difference in this data sets were not statistically significant. The number of nests (p = 0.001) was positively correlated with the proportion of Ki67 positive cells.
CONCLUSIONS: A small sample of patients were included and there was no follow-up.
CONCLUSIONS: BRAF V600E gene mutations were associated with high proliferative activity and distinct histopathological features in congenital melanocytic nevi.

BACKGROUND: Pigmented epithelioid angiomyolipoma is a variant of epithelioid angiomyolipoma (EAML) that has not previously been described in children with tuberous sclerosis.
METHODS: A 15-year-old boy with tuberous sclerosis had a rapidly enlarging renal mass associated with a left lung nodule. Microscopically it was a pigmented EAML, confirmed by immunohistochemistry.
CONCLUSIONS: The pigmented variant of EAML can arise and metastasize from the kidney of a teenager with tuberous sclerosis.

In this study, the clinicopathologic features and survival outcomes of patients with hyperpigmented MF from a single tertiary referral center database were retrospectively evaluated. Hyperpigmented MF accounted for 10.9% (14/128) of all MF cases. The mean age at diagnosis was 46.9 years, and the female-to-male ratio was 1:1.3. Concurrent hypopigmented, ichthyosiform, and poikilodermatous lesions were detected in 21.4%, 14.3%, and 14.3% of the patients, respectively. Histopathologically, most patients (85.7%) showed interface change with pigment incontinence. Double negative (CD4- and CD8-) immunophenotypes were more frequent in patients with hyperpigmented MF (25%) than in those with other MF subtypes (9.8%). Most patients (85.7%) had early-stage disease at diagnosis. The survival outcomes did not differ significantly between hyperpigmented and other MF subtypes. In conclusion, hyperpigmented MF often accompanies other atypical MF variants and is frequently associated with atypical immunophenotypes. The outcomes of hyperpigmented MF are comparable to those of other MF subtypes.

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