Biomedical subjects
Publications and source records attributed to A R Rhodes.
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Cutaneous melanoma is rapidly becoming a potentially curable cancer if it is detected and properly treated in an early phase of development. Unlike other cancers, which are usually hidden from detection until they are relatively large or metastatic disease has occurred, cutaneous melanoma is readily detectable simply by examining the skin. Information is now available that will be useful in selecting individuals at greatest risk. The most important melanoma risk factors (in decreasing order of importance) for a given individual are as follows: a persistently changed or changing mole, adulthood, irregular varieties of pigmented lesions (including dysplastic moles and lentigo maligna), a congenital mole, Caucasian race, a previous cutaneous melanoma, a family history of cutaneous melanoma, immunosuppression, sun sensitivity, and excessive sun exposure. Selective screening and appropriate treatment of individuals who have these risk factors may reduce the morbidity and mortality of cutaneous melanoma.
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Disseminated intravascular coagulation and purpura fulminans developed in association with septicemia and meningitis due to Candida tropicalis in an 18-year-old female immunosuppressed renal allograft recipient. Although systemic Candida infection was initially suspected, blood cultures showed no growth of this organism until after its identification in the dermis of a skin biopsy specimen obtained from the site of purpura fulminans. This case illustrates the association between Candida sepsis and purpura fulminans, and demonstrates the usefulness of skin biopsy of purpura fulminans in the early diagnosis of Candida sepsis.
There are several recognizable melanocytic precursors of cutaneous melanoma. These precursors include lentigo maligna, dysplastic melanocytic nevi, congenital nevi (of any size), and darkly pigmented lesions of acral surfaces and mucous membranes. Lentigo maligna is an uncommon melanocytic dysplasia, present in 3 per 1000 individuals over the age of 50 years and accounting for 4 percent of all cutaneous melanomas. Dysplastic melanocytic nevi are present in 2 per cent of white adults, and may account for at least a fifth of cases of cutaneous melanoma. Congenital nevomelanocytic nevi are present in 1 per cent of newborns; the vast majority of congenital nevi are smaller than 3 to 4 cm in diameter, while very large congenital nevi are present in 1 in 20,000 to 1 in 500,000 newborns. Very large congenital nevi account for less than 0.1 percent of cutaneous melanomas, whereas small varieties of congenital nevi may account for 15 percent of cutaneous melanomas. If individuals with lentigo maligna live long enough, possibly a third to a half are said to develop melanoma. This figure may be biased high. Persons with dysplastic melanocytic nevi in the familial melanoma setting have an estimated lifetime risk of developing melanoma approaching 100 per cent. Persons with dysplastic melanocytic nevi in other settings may have a lifetime melanoma risk of 18 per cent. Persons with congenital nevi of any size may have a lifetime melanoma risk of at least 5 per cent. Early recognition of these precursor melanocytic tumors, particularly in high-risk individuals (i.e., those with a personal or family history of melanoma), and careful photographic follow-up or prophylactic excision of these lesions may be the most effective means of reducing the morbidity and mortality of cutaneous melanoma. The impact of routine screening and excision of presumed melanoma precursors is unknown. Clinical judgment is required to balance the theoretical risk of melanoma associated with a given precursor and the known risks of surgery and anesthesia for a given individual. It must be kept in mind that the vast majority of acquired melanocytic nevi in adults are harmless. Probably even the majority of dysplastic nevi and small congenital nevi will remain unchanged throughout life. The simple recognition of the existence of melanoma precursors will heighten suspicion for these lesions and raise awareness of the earliest signs of malignant change.(ABSTRACT TRUNCATED AT 400 WORDS)
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Congenital pigmented arrector pili hamartomas are unique malformations of epidermis and pilar apparatus usually appearing as localized, lightly pigmented, hairy plaques. Characteristic microscopic features include smooth-muscle proliferation similar to irregularly disposed arrectores pilorum, and slight elongation of epidermal rete with hypermelanosis of the basal unit. An otherwise normally developed child who had this hamartoma at birth is described in an attempt to clarify the relationship between pilar smooth-muscle hamartomas and Becker's melanosis. We propose that these two entities belong at different poles of the same developmental spectrum of hamartomatous change.
We investigated the genetic aspects of congenital nevomelanocytic nevi (CNN) by comparing the prevalence rate of CNN in sibs of probands to that of CNN in newborn infants. Probands included all individuals with small (less than 40 mm) CNN registered photographically during 1982 in a children's hospital dermatology service. A CNN was defined on the basis of gross appearance and presence (according to parents) within the first 2 weeks of life. The 39 probands with small CNN had a total of 65 sibs. Eight of the 65 (12.3%) also had one or more small CNN. This prevalence rate in sibs is 11 times the population-based prevalence rate of CNN in newborn infants (1.1%) based on a published report surveying newborn infants in the same city within the past decade. In five of our 39 study families we also detected an affected parent with CNN. We conclude that small CNN may aggregate in families. Autosomal dominant inheritance with incomplete penetrance or multifactorial determination could account for this observation.
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A reliable microscopic differentiation of nevomelanocytic nevi (NMNs) as congenital or acquired would be useful in defining a histogenic relationship between cutaneous melanoma and congenital NMN. In order to delineate histologic differences between congenital NMN and acquired NMN, a standardized assessment was conducted blindly, using a sample of consecutive surgical specimens of NMN submitted to a children's hospital pathology file. Despite significant histologic differences between congenital NMN and acquired NMN, the lack of a reliable prevalence rate for the proportion of congenital NMNs among all NMN specimens submitted for pathologic examination precludes a precise estimate of predictive value for diagnosing a given NMN as congenital or acquired based on histologic features alone. The results of this study can be used neither to support nor to refute a histologic association between cutaneous melanoma and congenital NMN.
A multivariate analysis was performed on 20 clinical and histologic variables from 327 Stage I prospectively studied melanoma patients who underwent elective regional lymph node dissection (ERLD). Primary tumor thickness, microscopic satellites, and the elapsed interval between diagnosis and ERLD, were selected as the combination of variables that were most highly associated with clinically occult regional lymph node metastases (P = 10(-15), model chi-square). Microscopic satellites were defined as tumor nests, greater than 0.05 mm in diameter, in the reticular dermis, panniculus, or vessels beneath the principal invasive tumor mass but separated from it by normal tissue on the section in which the Breslow measurement was taken. The probability of finding nodal metastases for melanomas less than 0.75 mm thick was 0% (0/41 patients); for those 0.76-1.50 mm, 4% (4/108); 1.51-3.0 mm, 14% (14/102); and greater than 3.0 mm, 39.5% (30/76). Primary melanomas greater than 1.50 mm thick with microscopic satellites were more often associated with nodal metastases than those of similar thickness without satellites (30/57 (53%) versus 14/121 (12%), P = 0.01). Some satellites probably represent intraspecimen metastases, while others do not. Any predictive model for occult regional lymph node metastases based on data from ERLD done less than 50 days after diagnosis may underestimate the prevalence of metastases.
We describe a 13-year-old girl with a cardiocutaneous syndrome characterized by an atrial myxoma, pigmented lesions of the skin and genital mucosa, and opalescent papules and dermal nodules of the skin and tongue. Her pigmented lesions included black macules of the face and vulva, brown macules of the lips and perioral skin, multiple blue nevi, and a congenital nevomelanocytic nevus. The black and brown macules of the face and vulva consisted of lentiginous proliferations of large, intensely dopa-reactive melanocytes. The opalescent papules and dermal nodules had histologic, ultrastructural, and histochemical characteristics of myxomas. During follow-up, the patient developed thyroid nodules, which were composed of mixed papillary and follicular hyperplasia. This case emphasizes the necessity of a cardiac evaluation for a potentially fatal (and surgically treatable) atrial myxoma in individuals with multiple melanocytic and myxomatous tumors of the skin and mucosa.
Ultrastructural studies were conducted in order to determine morphologic and functional differences in melanocytes and melanosomes in PUVA lentigines and solar lentigines, and light-protected buttock skin. Compared to melanocytes in solar lentigines from 7 subjects and light-protected buttock skin from 5 subjects (none of these subjects had received UV radiation therapy), melanocytes in PUVA lentigines from 6 subjects generally had longer and more numerous dendrites, and showed more active melanogenesis. Basal keratinocytes in PUVA lentigines had a significantly increased frequency of large, single melanosomes, and revealed significantly larger individual melanosomes within compound melanosomes. Other findings in some PUVA lentigines included the close apposition of Langerhans cells to melanocytes, and atypical nuclear, cytoplasmic and melanosomal alterations, including melanosomal pleomorphism and melanin macroglobules. The presence of relatively large and predominantly single melanosomes in basal keratinocytes of PUVA lentigines suggests more active melanogenesis and/or an irreversible somatic alteration. It will be important to determine the clinical course and ultrastructural findings of PUVA lentigines that persist long after PUVA is discontinued.
A cytochemical study of acid phosphatase (AcPase) activity was conducted in normal epidermal melanocytes from both sun-exposed and sun-protected human skin to define the relationship between enzyme activity and melanosome formation. In the perikarya of melanocytes of both sun-exposed and sun-protected skin, it was determined that only a small proportion of stage 1 and 2 melanosomes had AcPase activity (20-33% and 9-26%, respectively). The proportion of AcPase-positive melanosomes in perikarya increased in stage 3 (39-56%), reaching a maximum in stage 4 (67-84%). In the dendrite of melanocytes, where melanosomes were mostly in stages 3 and 4, the vast majority of melanosomes demonstrated AcPase activity (79-87% and 88-93%, respectively). The preferential incorporation of AcPase in the later stages of melanogenesis is more consistent with a possible role for this enzyme in the degradation or transfer of melanosomes, rather than as an essential component in the early process of melanization.
A 9 1/2-year-old girl was seen with 20-nail dystrophy. Lichen planus was suspected and further examination revealed other lesions localized to the oral mucosa. The diagnosis was confirmed as lichen planus by biopsy of tissue from the oral lesions. Careful examination of all mucocutaneous surfaces is recommended before accepting the diagnosis of so-called isolated 20-nail dystrophy of childhood.
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