Adverse Events of Light-Assisted Hair Removal: An Updated Review

BACKGROUND

With light-assisted hair removal becoming widely used, reports of adverse effects are increasing.

OBJECTIVE

To review all the reported optical incidents and cutaneous complications of laser or intense pulse light-assisted hair removal.

METHODS

A PubMed database systematic search was performed to identify studies reporting such adverse events before July 2022 using the Mesh terms "adverse effects" AND "hair removal" AND ("laser" OR "intense pulse light").

RESULTS

Altogether, 358 references were identified. After excluding duplicates, unrelated articles, guidelines, and conference abstracts, then adding references from studies bibliography, 104 publications were included. Ocular incidents consisted of anterior uveitis, iritis and iris atrophy, pupillary distortion, posterior synechiae, anterior chamber pigment, and cataracts in the anterior subcapsular region. Cutaneous complications consisted of pain, burns, folliculitis, leukotrichia, paradoxical hypertrichosis, pigmentary changes, changes in nevi, pili bigemini, herpes infection, hyperhidrosis, bromhidrosis, Fox-Fordyce disease, and frostbite from the cooling system. They were mostly correlated to skin type and body area as well as to light device and set parameters. Intense pulse light devices were found to be less painful than alexandrite laser, yet more painful than diode laser; Nd:YAG laser had the highest pain score.

CONCLUSION

Optical incidents can be systematically avoided. Cutaneous complications are usually related to professional errors and patient characteristics. Better knowledge of laser physics and adequate training of laser operators are key recommendations to avoid undesirable side effects. Safety recommendations help prevent most of the reported complications.

Selected Lesions Featuring Giant Cells

Many neoplasms of the soft tissues feature giant cells, but this article covers entities in which giant cells are a striking feature. Specifically, we consider tenosynovial giant cell tumor (localized and diffuse types; giant cell tumor of tendon sheath, and pigmented villonodular tenosynovitis), reticulohistiocytoma, juvenile xanthogranuloma, giant cell fibroblastoma (a variant form of dermatofibrosarcoma protuberans), giant cell angiofibroma (which is essentially a giant cell-rich form of solitary fibrous tumor), and phosphaturic mesenchymal tumor.

CD99 expression in dermatofibrosarcoma protuberans and dermatofibroma

BACKGROUND

Differentiating between dermatofibrosarcoma protuberans (DFSP) and hypercellular dermatofibroma (DF) can sometimes be challenging, and a panel of immunostains is often employed. Expression of conventional markers oftentimes overlaps. We evaluated CD99 expression in DFSP and DF and its utility in distinction between these 2 entities.

METHODS

CD99 immunostaining was performed on 34 DFSPs and 24 hypercellular DFs. The intensity of staining was graded as "weak," "moderate," or "strong," and the proportion of positive cells was graded as follows: "scattered" when individual cells comprised <5% of the total cellularity of the lesion; "focal" with >5% but <25% of the cells; or "diffusely distributed" with staining of >25% of lesional spindle cells.

RESULTS

Overall, DFSPs showed positive CD99 staining in 21 (61.76%) cases. Moderate and weak patterns of staining were the most frequent, seen in 13 (38.2%) and 7 (20.6%) cases, respectively. CD99 staining in DFSPs was predominantly scattered or patchy (4 and 11 lesions respectively) with less than 25% of cells expressing CD99. In comparison, all 24 DF cases showed strong CD99 positivity in >25% of the spindle cell component (P = 0.0003). The most striking difference related to the distribution of staining. In DFSP, tumor cells in the superficial dermis, when present, were always CD99 negative. In contrast, DF cells in the superficial dermis always demonstrated strong CD99 positivity.

CONCLUSIONS

DF strongly expresses CD99 in a diffuse pattern that may serve as evidence in distinction from DFSP. As the differences in staining were most pronounced in the superficial portions of the tumor, CD99 staining may be well suited to superficial biopsy specimens, where distinction in hematoxylin and eosin sections may be most problematic.

Effect of shRNA targeting mouse CD99L2 gene in a murine B cell lymphoma in vitro and in vivo

Mouse CD99 antigen-like 2 (mCD99L2) has previously been confirmed to be expressed in murine B lymphoma (A20) cells by our group. The present study aimed to establish a mCD99L2‑downregulated A20 cell line and to investigate the effect of shRNA targeting mCD99L2 in A20 cells in vitro and in vivo. Four pLenti6/mCD99L2 expression vectors containing the mCD99L2 shRNA-expressing cassette were constructed, transfected into A20 cells and stable mCD99L2-downregulated A20 subclones, termed A20-mCD99L2- cells, were established and identified by quantitative PCR and western blot analysis. Light and transmission electron microscopy, MTT assay, flow cytometry and immunofluorenscence labeling were used to observe the morphological, biological and phenotypic characteristics in vitro. Some of the A20-mCD99L2- cells exhibited H/RS‑cell like morphology, a decreased proliferative ability, a prolonged G2 phase and increased CD30 and CD15 expression. Upon injecting cells into nude or immunocompetent BALB/c mice, tumorigenesis, tumor growth, morphology and phenotypes in vivo were observed. A20-mCD99L2- cells induced tumors in nude and BALB/c mice, but with less potency in the latter compared with the controls. Similar morphological, biological and phenotypic characteristics were observed in the A20-mCD99L2- cell-induced tumors as those in vitro. Several cytokines including CD30T, IL-12p40/p70, IL-3, IFN-γ, CXCL16, MIP-1α and CD40 were upregulated following mCD99L2 downregulation when detected using antibody arrays. The results from western blot analysis indicated that the regulation of mCD99L2 expression may involve the activated nuclear factor-κB pathway in the murine B lymphoma cells. The present study provides data for further investigation into the mCD99L2 gene in tumor cells.

Fibrohistiocytic tumors and related neoplasms in children and adolescents

Fibrohistiocytic tumors (FHTs) in children and adolescents range from the benign fibrous histiocytoma, or dermatofibroma, to a variety of intermediate and malignant neoplasms, such as dermatofibrosarcoma protruberans and high-grade undifferentiated pleomorphic sarcoma (malignant fibrous histiocytoma). Those tumors as a group are comprised of fibroblasts, myofibroblasts, and histiocytes-dendritic cells with a variably prominent inflammatory infiltrate consisting of lymphocytes and eosinophils. Dendritic cells are also a major constituent of another group of neoplasms that include Langerhans cell histiocytosis, follicular and interdigitating cell sarcomas, and juvenile xanthogranuloma. These latter tumors are considered in this discussion for the sake of differential diagnosis and their possible histogenetic relationship to FHTs. Recent studies have suggested that the relationship between the fibroblast and histiocyte in the FHTs may reflect the intrinsic capacity to transdifferentiate from one to the other morphologic and functional state. The so-called "facultative fibroblast," as a cell with fibroblastic and histiocytic properties, was discussed in the context of the fibrous xanthoma 50 years ago. Possibly the entire histogenetic concept of FHTs should be reconsidered in light of current studies.

Extra nuchal-type fibroma associated with elastosis, traumatic neuroma, a rare APC gene missense mutation, and a very rare MUTYH gene polymorphism: a case report and review of the literature*

We report a case of an extra nuchal-type fibroma in a 51-year-old male suspected to have attenuated familial adenomatous polyposis (Gardner's syndrome), who presented with a longstanding buttock mass excised due to enlargement and pain. Histopathologically, lobules of haphazard, hypocellular, hyalinized collagen bundles replaced the dermis and subcutis and entrapped nerve bundles, mimicking Morton neuroma. Ramifying nerve twigs found around larger nerve fascicles showed the co-existence of traumatic neuroma. Elastic tissue stain revealed elastosis characterized by large, arborizing fibers lying between and within the hyalinized collagen bundles. Modified Masson's trichrome stain showed light blue staining of collagen bundles producing the hyalinized nodules with irregular, light red staining of collagen bundles at their periphery and within tumor collagen. Compression and/or degeneration of collagen and secondary elastosis with later entrapment by tumor collagen could explain this microscopic phenotype. By immunohistochemistry, tumor spindle cells expressed nuclear β-catenin and cyclin D1, mostly within regions of fibrosis implicating activation of the adenomatous polyposis coli (APC)-Wnt pathway. Genetic analysis showed a missense mutation in APC gene (c.7504G>A, p.G2502S in exon 15) and a functional homozygous polymorphism in the MUTYH gene (c.36+325G>C, (IVS1+5G/C)). Nuchal-type fibroma has been associated with Gardner's syndrome and trauma. In this patient, genetic predisposition coupled with repetitive, localized trauma and collagen degeneration may have provided the stimulus for the development of extra nuchal-type fibroma.

Changing pathology with changing drugs: skin cancer

Today skin cancer is mainly treated by surgical interventions. New findings concerning molecular biology and the signaling pathways in epithelial skin cancers such as basal cell carcinoma, squamous cell carcinoma or melanoma, and mesenchymal skin cancers such as angiosarcoma and dermatofibrosarcoma protuberans (DFSP) have identified new molecular targets for a systemic or local treatment approach. For DFSP there is an opportunity already today to reduce the intensity of surgical procedures by pretreatment with targeted therapy. This article highlights important aspects in several skin cancer types.

Update on immunohistochemical methods relevant to dermatopathology

CONTEXT

Dermatopathology covers a large variety of entities, some having very similar histologic appearances. Immunohistochemistry is an incredibly helpful tool that is useful in diagnosis as well as prognosis of selected skin tumors.

OBJECTIVE

To provide a comprehensive review of recent trends and immunohistochemical stains used by dermatopathologists. Emphasis is placed on new stains as well as novel uses of existing stains.

DATA SOURCES

All data were gathered from published journal articles available through the National Center for Biotechnology Information PubMed database.

CONCLUSIONS

New immunohistochemical targets are continually being found, contributing to more accurate diagnosis and classification of skin tumors. The presence of specific markers can be used to determine the aggressiveness of malignancies and design treatment strategies. In addition, application of existing stains can help determine intravascular spread of malignancy in primary cutaneous lesions. And use of rapid immunohistochemical staining techniques on frozen sections can assist in more complete excision of tumor margins. Immunohistochemistry is a highly versatile and growing tool of dermatopathologists.