Biochemistry, Physiology, and Tissue Interactions of Contemporary Biodegradable Injectable Dermal Fillers.

BACKGROUND: Injectable dermal fillers are becoming increasingly popular for soft tissue augmentation and rejuvenation. Most contemporary biodegradable products are derived from hyaluronic acid, calcium hydroxylapatite, or poly-L-lactic acid. Achievement of desired cosmetic outcomes is largely dependent on selection of the optimal injectable product based on the chemical composition, the physiologic interactions with surrounding tissue, product longevity, and a thorough understanding of potential adverse reactions. OBJECTIVE: To review and describe the biochemistry, physiology, and tissue interactions of the most commonly used contemporary biodegradable dermal fillers. METHODS: A thorough review of the literature was performed with additional review of pertinent clinical cases and corresponding histopathology. RESULTS: This article provides a comprehensive review of the biochemistry, physiology, and potential tissue interactions of the most commonly used biodegradable dermal fillers. The underlying biochemical properties of each product and how they contribute to specific physiologic and adverse tissue reactions is described. CONCLUSION: Understanding of the innate differences in the physical properties, and physiologic responses to soft tissue fillers allows clinicians to achieve desired aesthetic outcomes with fewer adverse events.

Concomitant mycosis fungoides and vitiligo: how mycosis fungoides may contribute to melanocyte destruction.

BACKGROUND: Few reports have described vitiligo developing in patients with cutaneous T-cell lymphoma (CTCL). OBJECTIVE: We sought to identify possible factors that might predispose patients with CTCL to vitiligo. METHODS: Patient demographics, CTCL disease characteristics and treatments were analyzed in 25 patients with CTCL who developed vitiligo. Cox proportional hazards modeling was used to identify associations of risk factors with the development of vitiligo. RESULTS: Younger age, later CTCL disease stage (stages IIB-IV) and presence of a CD8+CD4- mycosis fungoides phenotype were associated with the development of vitiligo. After adjusting for disease stage, increased risk of vitiligo was associated with methotrexate and CD4 antibody therapies (although the total number of patients with these was small), while decreased risk was associated with nitrogen mustard and PUVA therapies. CONCLUSIONS: No single feature was common to all of our patients, suggesting that multiple factors may contribute to the development of vitiligo in a patient-specific fashion.

Pilomatrix carcinoma: 13 new cases and review of the literature with emphasis on predictors of metastasis.

BACKGROUND: Pilomatrix carcinoma is a rare cutaneous tumor derived from follicular matrix cells with few cases documented in the literature. OBJECTIVE: We sought to better characterize this tumor by analyzing its epidemiologic, clinical, and histopathologic features in 13 new cases and by reviewing the literature. METHODS: All cases of pilomatrix carcinoma from a large regional dermatopathology practice were identified and analyzed by chart review for clinical and histopathologic characteristics. Similar characteristics were compiled from an additional 123 cases in the English-language literature. Cox proportional hazards regression models were used to determine risk factors associated with the development of metastasis for all identified metastatic tumors. RESULTS: Our 13 tumors were most common in middle-aged to older white men and presented mostly on the head/neck. Histopathologically, tumors were asymmetric, were poorly circumscribed, were composed of basaloid and "ghost" cells, had frequent atypical mitoses, and had infrequent lymphovascular invasion. Wide excision was considered the most definitive treatment modality, but local recurrence was common. When analyzing all reported cases of metastasis using statistics, metastasis was significantly associated (hazard ratio 3.45, P < .0413) with local tumor recurrence. LIMITATIONS: The retrospective, single-center design and the reliance on electronic medical records are limitations. CONCLUSIONS: This study helps better characterize pilomatrix carcinoma and identifies potential predictors of metastasis.

Recognizing large-cell transformation of mycosis fungoides.

BACKGROUND: Although patients with mycosis fungoides (MF) typically experience an indolent disease course, a minority undergo a process of large-cell transformation (LCT), which often heralds more aggressive disease and shortened survival. Regrettably, most dermatologists are unfamiliar with LCT, and even fewer understand how to recognize it clinically. Because a diagnosis of LCT typically triggers more aggressive therapy and/or referral to cutaneous T-cell lymphoma (CTCL) centers, it is paramount for clinicians to be able to recognize suspect lesions visually. OBJECTIVE: LCT is diagnosed histologically; however, diagnostic biopsy is performed only if transformed lesions are suspected clinically. Because the literature provides little information on what clinical features should lead to suspicion of LCT, we sought to identify and categorize the presentations of LCT to aid in its recognition. METHODS: We identified 14 patients with biopsy-proven LCT confirmed by a board-certified dermatopathologist experienced with this diagnosis. The clinical presentations of LCT, timing of its evolution, and treatment regimens were evaluated by chart and photograph review. RESULTS: We devised 3 categories that clinically represent LCT: (1) LCT occurring as a new, solitary nodule within a classic MF patch or plaque, (2) LCT occurring as abrupt onset of multiple scattered papules and/or nodules without spontaneous resolution, and (3) LCT occurring within new or enlarging tumors. LIMITATIONS: A larger number of reviewed cases might reveal additional clinical presentations of LCT. CONCLUSIONS: Dermatologists may use our categories of clinical indicators to recognize and diagnose LCT earlier, allowing implementation of more aggressive treatment regimens when appropriate.

Liver kinase B1 (LKB1) in the pathogenesis of epithelial cancers.

LKB1 acts as a master kinase, with its major protein targets being the family of AMPKs. Through activation of multiple signaling pathways, LKB1's main physiologic functions involve regulating cellular growth, metabolism, and polarity. Germline mutations in LKB1 result in Peutz-Jeghers Syndrome, a rare cancer susceptibility syndrome. In addition, multiple LKB1 mutations have been identified in sporadic cancers, especially those of the lung. Recent studies from a variety of murine models have helped characterize LKB1's role in the pathogenesis of epithelial cancers. In some tumor types, LKB1 might function chiefly to suppress cell growth or invasion, while in other cases, it may serve to prevent metastasis. Moreover, molecular signatures of individual tumors likely influence LKB1's operational role, as multiple studies have shown that LKB1 can synergize with other tumor suppressors and/or oncogenes to accelerate tumorigenesis. To date, LKB1 has been considered mainly a tumor suppressor; however, some studies have suggested its potential oncogenic role, mainly through the suppression of apoptosis. In short, LKB1 is a tissue and context-specific kinase. This review aims to summarize our current understanding of its role in the pathogenesis of epithelial cancers.

Liver kinase B1 (LKB1) in the pathogenesis of UVB-induced murine basal cell carcinoma.

LKB1, a known tumor suppressor, is mutated in Peutz-Jeghers Syndrome (PJS). It is responsible for the enhanced cancer risk in patients with PJS. Dysregulation of LKB1-dependent signaling also occurs in various epithelial cancers. UVB alters the expression of LKB1, though its role in the pathogenesis of skin cancer is unknown. Here we describe upregulation of LKB1 expression in UVB-induced murine basal cell carcinoma (BCC) and in human skin tumor keratinocytes. AMP-kinase and acetyl Co-A carboxylase, the downstream LKB1 targets, are also enhanced in this neoplasm. In addition, p-Akt, a kinase which inactivates GSK3ß by its phosphorylation, is enhanced in BCCs. Consistently, an accumulation of p-GSK3ß and an increase in activated nuclear ß-catenin are found. mTOR signaling, which is also inhibited by LKB1, remains upregulated in BCCs. However, a marked decrease in the expression of sestrins, which function as potent negative regulators of mTOR is observed. Metformin, a known chemical inducer of this pathway, was found effective in immortalized HaCaT keratinocytes, but failed to activate the LKB1-dependent signaling in human carcinoma A431 cells. Thus, our data show that the LKB1/AMPK axis fails to regulate mTOR pathway, and a complex regulatory mechanism exists for the persistent mTOR activation in murine BCCs.