Phenotype of cranioectodermal dysplasia with different hair and bone abnormalities

We report on a 3-year-old boy with hair abnormalities and a generalized bone dysplasia. He had very short, sparse hair and craniosynostosis. His stature, growth, and limb lengths were normal, as was his neurological development. While this phenotype has some resemblance to cranioectodermal dysplasia, the radiographic and hair abnormalities are different. Histological studies showed abnormalities in the internal root sheath of the hair follicle and the hair shaft. These findings define a new ectodermal dysplasia syndrome of unknown cause.

Longwave ultraviolet radiation (UVA, 320-400 nm)-induced tan protects human skin against further UVA injury

The protective effect of a UVA (320-400 nm) induced tan against cutaneous injury by further UVA-irradiation was studied by evaluating the histopathologic changes in tanned and untanned normal human buttock skin 24 h after exposure to 2 and 4 minimal erythema doses of UVA. In each subject there were fewer polymorphonuclear leukocytes and less endothelial cell prominence and vessel wall necrosis in the UVA tanned skin than in the untanned UVA-irradiated skin. In the tanned control and tanned UVA-irradiated skin there was a prominent mononuclear cell inflammatory infiltrate that was much greater than in untanned skin. In immunoperoxidase stained tissue sections, the mononuclear cells were predominantly T cells, and in all of the specimens the number of phenotypic helper/inducer cells exceeded the phenotypic cytotoxic/suppressor cells. This demonstrates that a UVA tan provides photoprotection against acute UVA exposure. In addition, tanning, with or without further UVA-irradiation, was associated with a mononuclear cell inflammatory infiltrate.

Selective photothermolysis of cutaneous pigmentation by Q-switched Nd: YAG laser pulses at 1064, 532, and 355 nm

Exposure of skin to nanosecond-domain laser pulses affects the pigmentary system by a process called selective photothermolysis, in which melanosomes and pigmented cells are preferentially altered. Due to the broad absorption spectrum of melanin, this effect may occur with wavelengths that penetrate to vastly different depths within tissue, potentially producing different biologic responses. The effects of single near-ultraviolet (355 nm), visible (532 nm), and near infrared (1064 nm) pulses of 10-12 nsec duration were determined in guinea pig skin using gross, histologic, and electron microscopic observations. Threshold response in pigmented skin was a transient immediate ash-white discoloration, requiring 0.11, 0.20, and 1.0 J/cm2, at 355, 532, and 1064 nm, respectively. At each wavelength, melanosomes were ruptured within keratinocytes and melanocytes, with cytoplasmic and nuclear alterations. Delayed epidermal depigmentation occurred, followed by gradual repigmentation. Deep follicular cells were altered only at 532 and 1064 nm, which produced permanent leukotrichia. The action spectrum for threshold response was consistent with mechanisms implied by selective photothermolysis. These data may be useful for consideration of treatment for cutaneous pigmentation abnormalities or unwanted follicular pigmentation, or both.

The systemic administration of gamma interferon inhibits collagen synthesis and acute inflammation in a murine skin wounding model

The ability of gamma interferon (IFN-gamma) to affect cutaneous collagen synthesis in vivo was examined in a murine wounding model. Reproducible areas of full-thickness skin necrosis were produced by argon laser radiation. Mice received recombinant murine IFN-gamma (rMuIFN-gamma) (8.7 X 10(3) units/hr) over 14 d via osmotic pumps implanted subcutaneously or intraperitoneally. At 14 and 21 d after wounding, there was less fibrous tissue in healing scars of treated animals as determined by light and transmission electron microscopy. Associated with the decrease in connective tissue was an increase in the acid mucopolysaccharide content of healing scars, which was largely hyaluronate. Quantitative image analysis of electron micrographs confirmed that less collagen was present in healing scars of animals receiving rMuIFN-gamma. The mean cross-sectional area of collagen fibers was smaller in specimens from treated mice, but no difference was seen in the size of collagen fibrils. The time required to obtain full skin closure was also delayed 23%-27% in treated animals. Using this injury model, we also found that rMuIFN-gamma significantly reduced the degree of perilesional erythema surrounding the laser injury sites and, in the first 6 d after wounding, the degree of polymorphonuclear infiltrate present histologically at lesional sites. Indeed, rMuIFN-gamma also decreased the cutaneous accumulation of neutrophils induced by known proinflammatory mediators, such as interleukin 1 and activated serum. Thus, systemically administered IFN-gamma not only down-regulates collagen synthesis in the skin but also modulates in a previously unrecognized manner: neutrophil accumulation at sites of tissue injury in vivo.

Comparison of acral nevomelanocytic proliferations in Japanese and whites

The preponderance of malignant melanomas that occur in the Japanese population affect the palmar and plantar areas, in contrast to those of whites, which occur predominantly on the head, neck, and trunk. Furthermore, a precursor lesion, the dysplastic nevus, has been well defined in nonacral white skin but not in the Japanese. In this paper, a similarity between benign and atypical acral nevomelanocytic proliferations in Japanese and whites is described. However, it appears that in the Japanese group the melanocytes in benign and atypical proliferations are less dendritic than those noted in whites, and, in both groups, extensive pigmentation was noted in both the epidermal and dermal components of benign and malignant lesions in this limited review. A practical approach to classifications of atypism is, likewise, offered.

Pigmented guinea pig skin irradiated with Q-switched ruby laser pulses. Morphologic and histologic findings

Q-switched ruby laser pulses cause selective damage to cutaneous pigmented cells. Repair of this selective damage has not been well described. Therefore, using epilated pigmented and albino guinea pig skin, we studied the acute injury and tissue repair caused by 40-ns, Q-switched ruby laser pulses. Gross observation and light and electron microscopy were performed. No specific changes were evident in the albino guinea pigs. In pigmented animals, with radiant exposures of 0.4 J/cm2 or greater, white spots confined to the 2.5-mm exposure sites developed immediately and faded over 20 minutes. Delayed depigmentation occurred at seven to ten days, followed by full repigmentation by four to eight weeks. Regrowing hairs in sites irradiated at and above 0.4 J/cm2 remained white for at least four months. Histologically, vacuolation of pigment-laden cells was seen immediately in the epidermis and the follicular epithelium at exposures of 0.3 J/cm2 and greater. Melanosomal disruption was seen immediately by electron microscopy at and above 0.3 J/cm2. Over the next seven days, epidermal necrosis was followed by regeneration of a depigmented epidermis. By four months, melanosomes and melanin pigmentation had returned; however, hair follicles remained depigmented and devoid of melanocytes. This study demonstrates that selective melanosomal disruption caused by Q-switched ruby laser pulses leads to transient cutaneous depigmentation and persistent follicular depigmentation. Potential exists for selective treatment of pigmented epidermal and dermal lesions with this modality.

Visible action spectrum for melanin-specific selective photothermolysis

The skin of black and albino guinea pigs was irradiated with single, 750 nsec-long laser pulses at 435, 488, 530, and 560 nm in order to determine an action spectrum for the gross threshold response of immediate epidermal whitening. In addition, the immediate and delayed gross and histologic changes induced at, above, and below the threshold radiant exposures at all four wavelengths were studied. The action spectrum in the black guinea pigs was consistent with the reported absorption spectrum of DOPA-melanin. Histologically, there was epidermal damage immediately after radiant exposures at and above threshold at all four wavelengths. In addition, radiant exposures greater than threshold caused an immediate decrease in stainable epidermal pigment that was most marked at 435 and 488 nm. The healing response was also wavelength- and dose-dependent. Seven days after above-threshold exposures, there was little epidermal pigment in the 435 nm specimens. As wavelength increased, there was progressively more pigment, and in the 560 nm specimens, the epidermal pigment was equivalent to that seen in nonirradiated black guinea pig control specimens. Seven days after subthreshold radiant exposures, there was increased epidermal pigmentation and melanocytes at all four wavelengths. This was the most pronounced in the 435 nm specimens. There was no observable epidermal damage in albino guinea pig skin.

Induction of dermal and subcutaneous inflammation by recombinant cachectin/tumor necrosis factor (TNF alpha) in the mouse

The ability of cachectin/tumor necrosis factor (TNF alpha) to induce acute dermal and subcutaneous inflammation was examined in a murine model. A number of other proteins, and diluent alone were examined as controls. After subcutaneous injection into the mouse footpad, recombinant human TNF alpha (rHuTNF alpha) induced acute inflammation with an initial marked dermal and subcutaneous neutrophil infiltrate by approximately 3 h, with a peak between 4 and 24 h and resolution by 79 h. Recombinant interleukin-2, cytochrome c, and heat-inactivated rHuTNF alpha induced negligible inflammation. Recombinant human lymphotoxin (TNF beta), another control protein, also induced acute inflammation in our system. Because TNF alpha and TFN beta are partially homologous, they may be acting through a similar mechanism. This pro-inflammatory effect of TNF alpha may result from chemotactic activity as well as by induction of secondary mediators. Inflammation induced by TNF alpha was partially suppressed by indomethacin treatment, suggesting that products of the cyclo-oxyganase pathway may mediate a portion of the inflammation involved. Five daily injections of rHuTNF alpha into the mouse footpad resulted in a predominantly mononuclear infiltrate and focal fibrosis. These results suggest that TNF alpha may be an important mediator of acute inflammation in vivo and might provide a signal for the production of collagen.

Melanosomes are a primary target of Q-switched ruby laser irradiation in guinea pig skin

The specific targeting of melanosomes may allow for laser therapy of pigmented cutaneous lesions. The mechanism of selective destruction of pigmented cells by various lasers, however, has not been fully clarified. Black, brown, and albino guinea pigs were exposed to optical pulses at various radiant exposure doses from a Q-switched, 40 nsec, 694 nm ruby laser. Biopsies were analyzed by light and electron microscopy (EM). Albino animals failed to develop clinical or microscopic evidence of cutaneous injury after irradiation. In both black and brown animals, the clinical threshold for gross change was 0.4 J/cm2, which produced an ash-white spot. By light microscopy, alterations appeared at 0.3 J/cm2 and included separation at the dermoepidermal junction, and the formation of vacuolated epidermal cells with a peripheral cytoplasmic condensation of pigment. By EM, enlarged melanosomes with a central lucent zone were observed within affected epidermal cells at 0.3 J/cm2. At 0.8 and 1.2 J/cm2, individual melanosomes were more intensely damaged and disruption of melanosomes deep in the hair papillae was observed. Dermal-epidermal blisters were formed precisely at the lamina lucida, leaving basal cell membranes and hemidesmosomes intact. Possible mechanisms for melanosomal injury are discussed. These observations show that the effects of the Q-switched ruby laser are melanin-specific and melanin-dependent, and may be useful in the selective destruction of pigmented as well as superficial cutaneous lesions.

Gamma-interferon inhibits collagen synthesis in vivo in the mouse

Subcutaneous implantation of osmotic pumps into CAF1 mice resulted in the formation of thick fibrous capsules around the pumps. When pumps were loaded with recombinant murine gamma-interferon (rMuIFN-gamma) to deliver 2 X 10(3) U/h for 14 d, there was a marked decrease in thickness and collagen content of the capsules from rMuIFN-gamma-treated animals compared with capsules from animals receiving diluent alone. The collagen content of the capsules was estimated by hydroxyproline analysis of the tissue and by quantitative electron microscopy of collagen bundles. Heat-inactivated rMuIFN-gamma failed to reduce the fibrotic response in this assay. These results provide compelling evidence that gamma-interferon can down-regulate collagen synthesis in vivo and suggest the possibility that this lymphokine may be useful in the treatment of disease states characterized by excessive fibrosis.

Atypical angiomatosis in polyarteritis nodosa

Biopsies from an area of livedo reticularis and adjacent to a leg ulcer in a woman with polyarteritis nodosa showed florid angioendothelial proliferation simulating angiosarcoma. This angioproliferative reaction has not been described previously in polyarteritis nodosa. Its microscopic differentiation from angiosarcoma is important.

Selective ablation of atheromas using a flashlamp-excited dye laser at 465 nm

Ablation of human atheromas with laser pulses that had only a small effect on normal artery tissue was shown in vitro in air and under saline using 1-mu sec pulses at 465 nm from a flashlamp-excited dye laser. At this wavelength, there is preferential absorption in atheromas due to carotenoids. The threshold fluence for ablation was 6.8 +/- 2.0 J/cm2 for atheromas and 15.9 +/- 2.2 J/cm2 for normal aorta tissue. At a fluence of 18 J/cm2 per pulse, the ablated mass per unit of energy ranged from 161 to 370 micrograms/J for atheromas and from 50 to 74 micrograms/J for normal aorta tissue. Ablation products consisted of cholesterol crystals, shredded collagen fibers, and small bits of calcific material. Most debris was less than 100 micron in diameter, but a few pieces were as large as 300 micron. High-speed photography of ablation in air suggested explosive ejection of debris, caused by vapor formation, at speeds on the scale of 300 m/sec. Histological analysis showed minimal thermal damage to residual tissue. These data indicate that selective laser ablation of atheromas is possible in vitro.

The spectrum of minimal deviation melanoma: a clinicopathologic study of 21 cases

A retrospective study of 21 patients with the histopathologic diagnosis of minimal deviation melanoma (MDM; n = 18) and borderline melanoma (BM; n = 3) was undertaken to determine the prognosis for these patients compared with that for patients with other types of malignant melanoma. The findings indicate that the prognosis for these uncommon nevomelanocytic tumors is somewhat better than that for other malignant melanomas. Follow-up periods in this series ranged from 18 to 96 months (mean, 57 months). Primary lesions ranged in thickness from 1.6 to 10.4 mm. The histopathologic subtypes included the Spitz variant (nine patients), the spindle cell variant (six patients), the combined spindle and epithelioid cell type (three patients), and the small epithelioid cell type (three patients). Only two of the patients died of widespread metastatic disease. Comparison of the histologic and clinical prognostic indicators of mortality in patients who have malignant melanoma with the clinical and pathologic features seen in this series of 21 patients would appear to indicate a diminished tendency toward metastatic or recurrent disease in patients with MDM and BM.

Erythema multiforme in a patient with T cell chronic lymphocytic leukemia

A patient with T4+ (helper-inducer) T cell chronic lymphocytic leukemia developed an erythema multiforme-like eruption, the diagnosis of which was supported by routine light microscopic findings. Immunopathologic studies using monoclonal antibodies demonstrate that despite an overwhelming majority of leukemic T4+ cells in the peripheral blood and dermal infiltrate, the predominant cells in the epidermal infiltrate are T8+ (cytotoxic-suppressor) cells. These findings are different from those seen in epidermotropic T cell leukemic infiltrates and are similar to those previously reported in erythema multiforme. Thus it is likely that the leukemic T4+ cells are participating in this cutaneous hypersensitivity reaction along with residual, normal T8+ cells.

Coexpression of neurofilament and keratin proteins in cutaneous neuroendocrine carcinoma cells

Four cases of neuroendocrine carcinomas (NECA) of the skin were studied by indirect immunofluorescence, using a monoclonal antikeratin antibody and a polyclonal antineurofilament antibody. Fifty to ninety percent and 80 to greater than 95% of the NECA cells stained with the antineurofilament antibody and the antikeratin antibody, respectively. Using double-labeling indirect immunofluorescence we could also demonstrate that, in 3 cases studied, some of the NECA cells, but not all, stained with both antikeratin and antineurofilament antibodies. These results, together with the recent knowledge of the intermediate filament protein type of normal Merkel cells (MC), tend to support the hypothesis that NECA cells do not originate from epithelial MC but from dermal neuroendocrine cells. A dual concept of intraepithelial MC and extraepithelial intradermal neuroendocrine cells, "from possible distinct origin," is proposed. Such a system has already been suggested for the neuroendocrine cells of the appendix and bronchial mucosae.

Lymphocyte subsets and Langerhans cells/indeterminate cells in erythema multiforme

A peroxidase-antiperoxidase study using monoclonal antibodies directed against T and B lymphocytes and Langerhans cells/indeterminate cells (LC/IC) was undertaken in order to understand more clearly the changes observed in erythema multiforme. At the various stages of development, from normal skin to target lesions, the quantity of inflammatory cells differed, but in each case the number of T8+ (cytotoxic/suppressor) cells was greater than the number of T4+ (helper/inducer) cells in the epidermis, whereas the latter exceeded the former in the dermis. Concomitant with the initial epidermis changes, there was an increase in the number of T6+ (LC/IC) cells in the upper and lower epidermis. With slight to moderate basal unit destruction, the number of LC/IC in the upper epidermis exceeded those in the lower epidermis. With severe basal unit destruction, there was a loss of LC/IC in the lower epidermis as detected by T6 reactivity. In fully formed blisters, the LC/IC in the upper half of the epidermis were decreased in parallel with the degree of epidermal necrosis. The character of the lymphocytic inflammatory infiltrate and redistribution in LC/IC are similar to those findings described in allergic contact dermatitis. The clinical, histologic, and immunopathologic changes in erythema multiforme appear to be due in part to cellular immune mechanisms with the lymphocyte as the predominant effector cell, and our data suggest a possible role for LC/IC in this disorder.

Minimal deviation melanoma: a histologic variant of cutaneous malignant melanoma in its vertical growth phase

Minimal deviation melanomas are uncommon nevomelanocytic tumors of indeterminate risk that appear as pigmented or nonpigmented skin nodules and are clinically diagnosed as Spitz nevi, hemangiomas, or malignant melanomas. They are characterized histologically by expansile growth in the papillary dermis with reticular dermal infiltration (minimal deviation type) or without reticular dermal invasion (borderline type). The tumors exhibit lesser cytologic atypia in their vertical growth phase (histologic variance) than observed in common forms of melanoma. A retrospective study of outcome in 21 patients with minimal deviation melanoma (mean tumor thickness by Breslow's measurement = 3.6 mm) disclosed recurrent disease in only 3 patients after a mean observation period of 57 months, supporting the impression that these tumors are not as biologically aggressive as common malignant melanomas. The histologic subtypes of minimal deviation melanoma are reviewed along with a discussion of the concept of histologic variance.