Catecholamine content of pigmented and nonpigmented tissues of the rabbit

Norepinephrine and dopamine content of various tissues from albine and nonalbino (black fur) rabbits were chemically determined. Although norepinephrine content of the nonpigmented iris (7.93 μg/g) and the pigmented iris (6.8 μg/g) did not differ significantly, the latter type contained very high amounts of dopamine (6.5 μg/g). As compared to that from the albino animal, the retina from nonalbino animals also contained slightly higher levels of dopamine. Thus, in addition to previously proposed neurotransmitter role of dopamine in the retina, it may also serve as precursor for the biosynthesis of melanin in the pigmented tissues.     

Striato-nigral astrocytic melanization

Summary Abnormal pigmentation was found in the striatum, pallidum and substantia nigra of two unrelated patients. Both had suffered from debilitating joint disease; there was no evidence of a progressive neurologic disorder. The pigment was localized in astrocytes and had the histochemical and electron microscopic features of melanin. The tissue changes suggest an anomaly of catecholamine metabolism either endogenous or induced by a still unknown exogenous factor.

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Zusammenfassung Bericht über 2 nicht verwandte Patientinnen, die eine abnormale Pigmentierung des Striatum und der Substantia nigra zeigten. Beide litten an debilitierenden Gelenkerkrankungen, aber hatten keine Geschichte neurologischer Symptomatik. Das abnormale Pigment fand sich in Astrocyten und hatte die histochemischen Eigenschaften und die Feinstruktur von Melanin. Die Veränderungen weisen auf eine Störung des Katecholaminstoff-wechsels hin, wobei offen bleibt, of dieselbe endogen ist oder auf unbekannten exogenen Faktoren beruht.

     

Melanocytic schwannoma: The cytologic aspect in fine-needle aspiration cytology (FNAC): Report of a case located in the spinal cord

We describe a case of intramedullary melanocytic schwannoma (MS) studied by means of fine-needle aspiration cytology (FNAC). The main cytologic features were (1) large three-dimensional clusters overshadowed by heavy pigment deposits which tested positive for Fontana Masson (and bleached with potassium permanganate), HMB-45, Vimentin, and S-100 protein; (2) loose syncytial monolayered sheets with very little pigment deposit; and (3) isolated spindle cells with polarized nucleus and tapered, thin cytoplasmic ends. Both the cytologic features and the immunophenotypic profile were nonspecific and on their own were insufficient to allow the diagnosis of MS to be reached. Clinical data and the magnetic resonance image (MRI) in conjuction with the cytologic findings did suggest the diagnosis of intramedullary MS. Diagn Cytopathol 1994;11:291–296. © 1994 Wiley-Liss, Inc.     

Is abnormal retinal development in albinism only a mammalian problem? Normality of a hypopigmented avian retina

The central retina in hypopigmented mammals is underdeveloped. In the outer retina this deficit is confined to rods. Also, many ganglion cells in temporal regions project inappropriately to the contralateral hemisphere. This study addresses the question of whether pigment-related abnormalities occur in the central retina of a non-mammal, the bird. Birds have a highly developed central retina, but unlike most mammals they do not have a significant uncrossed retinal projection. Consequently, examination of the retinae of hypopigmented birds will reveal whether there is a relationship between the two abnormalities. Also if one of the primary effects of albinism is centred on rods, then albino birds may not show a deficit, because their retinae are cone dominated. Retinae from normally pigmented and two forms of hypopigmented budgerigars (Melopsittacus undulatus) were studied. Measurements of layer thickness, cell density and cell size were made at a range of locations in the ganglion cell layer and in the inner and the outer nuclear layers. Estimates of cone numbers were also made. Each strain of bird had an area of increased retinal layer thickness in dorso-temporal regions, but not a fovea. Although there were variations in the measurements undertaken between the strains, none were pigment related or consistent with the abnormality found in the central retina in albino mammals. Consequently, the underdevelopment of the central retina seen in hypopigmented mammals does not occur in this bird. There are two possible explanations for this result. First, normal mammalian retinal development may depend partly on time-dependent interactions in the maturation of the retinal pigment epithelium and the neural retina. Although there is a common time table for the development of the mammalian visual system when expressed in terms of the caecal period, which is between conception and eye opening, the pace of retinal development in birds is accelerated, which may alter interactions between these regions. Second, as the bird retina is cone dominated, any deficits in albino strains may be relatively minor.     

Molecular genetic characterization of Congolese patients with oculocutaneous albinism

BackgroundOculocutaneous albinism (OCA) is an autosomal recessive genetic disorder associated with reduced or absent pigmentation in the skin, hair and eyes. OCA type 2 (OCA2) is the most common type in Sub-Saharan Africa, related to a recurrent 2.7 kb intragenic deletion. Genomic data from Congolese patients are lacking. We aimed to describe genetic causes of OCA2 in a cohort of Congolese persons with OCA, and explore possible genotype-phenotype correlations.MethodsA cross sectional study was conducted from January 2015 to December 2017 in Kinshasa, Democratic Republic of Congo (DRC). 165 Congolese unrelated families with non-syndromic OCA, identified through patients' associations, consented to participate to this study. All index cases were tested for the known 2.7 kb deletion involving the exon 7 of the OCA2 gene. Patients heterozygous for the deletion underwent Sanger sequencing of all exons and flanking sequences in the OCA2 gene. Family segregation was performed for candidate pathogenic variants.ResultsThe 2.7 kb deletion in the OCA2 gene was identified in 136/165 (82.4%) index cases, including 113 (68.5%) homozygotes and 23 (13.9%) heterozygotes. Sanger sequencing identified a pathogenic or likely pathogenic variant in the OCA2 gene in 12 out of 23 heterozygotes investigated (52.1%). Segregation analysis allowed us to locate the point mutation on the trans allele in the three patients from whom parental DNA was available.ConclusionThe OCA2 2.7 kb deletion is the major cause of non-syndromic OCA in Congolese patients recruited in this study, confirming results from other Sub-Saharan African populations. Several additional mutations were detected in OCA patient's heterozygote for the deletion, with to date no evidence for a second frequent founder mutation. The confirmation of a single mutation as the major cause will facilitate genetic counselling in this country.     

Nevus cells in axillary lymph nodes from radical mastectomy specimens

From 1977 to 1983, 44 cases with nevus cells in the capsule and trabeculae of axillary lymph node specimens from about 7000 mastectomies performed for primary breast cancer were found. This finding was therefore less than 1%. In 3 cases, the nevus cells were present in 2 nodes, whereas in 41 cases solitary nodes were involved. In 13 cases, nevus cells were present in nodes that also contained metastatic carcinoma. Silver impregnation of reticulin fibers is very useful for the differential diagnosis of nodal metastases of breast carcinoma.     

Pigmented adenomatoid odontogenic tumour

Summary A pigmented adenomatoid odontogenic tumour occurring in the mandible of a 12-year-old Japanese girl is reported. In addition to the characteristic histopathologic features, fine granules and coarse aggregates of melanin pigment were widely distributed in the spindle-shaped epithelial cells between duct-like structures, and dendritic cells containing melanin pigment were also distributed in tumour epithelium. The possible histogenesis of melanin pigment in the epithelial cells of the odontogenic lesions is discussed, although no firm conclusions could be drawn.     

Perivascular epithelioid cell tumor of the rib

We present a rare case of perivascular epithelioid cell tumor (PEComa) in the right 6th rib of a 28-year-old man. A plain computed tomography scan showed a round osteolytic lesion in the right 6th rib. The resected tissue contained a globular-shaped, soft tumor. Histologically, the tumor was rich in vasculature and exclusively composed of perivascular epithelioid cells with clear cytoplasm. Immunohistochemically, the tumor expressed diffusely a melanocyte marker, human melanoma black-45, and focally a myogenic marker, alpha-smooth muscle actin, but not an epithelial marker, AE1/AE3. Fontana-Masson-positive melanin pigments were present and c-kit receptor tyrosine kinase (CD117), involved in the development of melanocytes but not myogenic cells, was expressed in tumor cells. These findings indicate that the tumor is PEComa with some differentiation into melanocytes. Notably, owing to the unique location of the occurrence, the tumor occupied bone marrow tissues of the rib, resulting that the tumor has the potential for hematogenous metastasis. In spite of the lack of cells with severe atypia, necrosis, and numerous mitoses, tumor cells invaded into surrounding tissues and overexpressed cyclin D1. To the best of our knowledge, this is the first case report of PEComa arising from the rib with the signs of malignant potential.     

口腔婴儿黑色素神经外胚瘤的诊断要点及治疗原则

目的分析口腔婴儿黑色素神经外胚瘤(MNTI)的诊断要点与治疗原则。方法回顾性分析我院2011年7月至2013年7月期间收治的15例口腔婴儿黑色素神经外胚瘤患者的临床资料,研究其病理切片等。结果 在15例MNTI患儿中11例发病位置在上颌骨、2例在下颌骨、2例位于面颊部,在随访2¹8个月以后,有3例患儿确定在术后1个月复发,其中2例为可疑复发,1例因肿瘤局部扩散无法进行手术而死亡。结论在临床诊断检查口腔婴儿黑色素神经外胚瘤的发病部位、发病年龄时,要认真观察肿物颜色。婴儿的肿瘤生长速度较快,有局部侵袭性。同时手术后对患者定期随访,病理诊断需要和婴儿小圆细胞恶性肿瘤互相区别,首选治疗方式为保守的手术治疗。