Etiology and pathogenesis of squamous cell carcinoma

A 4-year retrospective assessment of postoperative complications in immunosuppressed patients following Mohs micrographic surgery

BACKGROUND

Many patients undergoing Mohs micrographic surgery for basal and squamous cell carcinomas are immunocompromised, yet postoperative complications associated with different types of immunosuppression are largely unstudied.

OBJECTIVE

To determine the incidence and nature of postoperative complications in immunosuppressed patients undergoing Mohs micrographic surgery.

METHODS

A retrospective cross-sectional chart review of patient characteristics, clinical characteristics, and complications.

RESULTS

Univariable analysis showed that compared with immunocompetence, immunosuppression was associated with 9.6 times the odds of postoperative complication (P = .003), with solid organ transplant recipients having 8.824 times higher odds (P = .006) and immunosuppressive therapy use displaying 5.775 times higher odds (P = .021). Surgical site infection (2.5%) and dehiscence (0.51%) were more prevalent among immunosuppressed patients, with an overall complication rate of 5.4% in the immunosuppressed population. Multivariable analysis of the association between immunosuppression and postoperative complication closely trended toward, but did not meet, significance (P = .056).

LIMITATIONS

This was a single-center, retrospective study. Other limitations include lack of non-solid organ transplants, limited medication-related data on nontransplant patients, and exclusion of cases involving patients with double transplants or multiple sources of immunosuppression.

CONCLUSIONS

Immunosuppression overall, particularly owing to solid organ transplant and immunosuppressive therapy use, places patients at higher risk for postoperative complications, including surgical site infection and wound dehiscence following MMS.

Ovis aries Papillomavirus 3 in Ovine Cutaneous Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is a common malignancy affecting humans and other animals. Papillomaviruses (PVs) are frequently reported as causal agents of cutaneous benign and malignant epithelial lesions in different animal species, but only few studies have investigated their role in ovine SCC. In this study, we explore the possible involvement of the Ovine aries PVs (OaPV1, OaPV2, OaPV3) in cutaneous SCC using an integrated histological and molecular approach. Forty cutaneous SCCs from different anatomical locations of Sardinian sheep and 40 matched non-SCC samples were evaluated histologically and by polymerase chain reaction (PCR) to assess the presence of ovine PVs. In addition, DNA in situ hybridization (ISH) and reverse transcription-polymerase chain reaction (RT-PCR) were carried out to evaluate the cellular localization and viral transcriptional activity, respectively. OaPV3 DNA was detected in 26 of 40 (65%) SCCs and in 12 of 40 (30%) non-SCC samples using PCR. OaPV1 and OaPV2 were not detected. OaPV3 viral DNA was observed by ISH in malignant epithelial squamous cells of 18 of 40 (45%) SCCs. In addition, the viral transcriptional activity was identified in 24 of 40 (60%) SCCs by RT-PCR. Notably, a higher viral positivity was observed in SCCs compared with non-SCC samples. The considerable infection rate of OaPV3 in the most common skin tumor of the sheep suggests that PV could represent a key factor in the onset of ovine SCC.

Risk of skin cancer in patients with diabetes mellitus: A nationwide retrospective cohort study in Taiwan

Increasing evidence suggests that certain types of cancers are more common in people with diabetes mellitus (DM). This study aimed to investigate the risk of skin cancer in patients with DM in Taiwan. In this retrospective cohort study using data from the Taiwan Longitudinal Health Insurance Research Database, the risk of developing overall skin cancer, including nonmelanoma skin cancer (NMSC) and melanoma, was compared by Poisson regression analysis and Cox regression analysis between the DM and non-DM cohorts. The DM cohort with newly diagnosed DM (n = 41,898) and a non-DM cohort were one-to-one matched by age, sex, index date, and comorbidities (coronary artery disease, hyperlipidemia, hypertension, chronic kidney disease, chronic obstructive pulmonary disease, and obesity). Compared with non-DM cohort statistically, for the people with DM aged ≥60 years, the incidence rates of overall skin cancer and NMSC were significantly higher (overall: DM/non-DM: number [n] = 99/76, incidence rate ratio [IRR] = 1.44, P = 0.02; NMSC: DM/non-DM: n = 94/66, IRR = 1.57, P = 0.005). By Cox regression analysis, the risk of developing overall skin cancer or NMSC was significantly higher after adjusting for sex, comorbidities, and overall diseases with immunosuppression status (overall: adjusted hazard ratio [AHR] = 1.46, P = 0.01; NMSC: AHR = 1.6, P = 0.003). Other significant risk factors were older males for skin cancer (overall: AHR = 1.68, P = 0.001; NMSC: AHR = 1.59, P = 0.004; melanoma: AHR = 3.25, P = 0.04), chronic obstructive pulmonary disease for NMSC (AHR = 1.44, P = 0.04), and coronary artery disease for melanoma (AHR = 4.22, P = 0.01). The risk of developing melanoma was lower in the DM cohort than in the non-DM cohort, but without significance (AHR = 0.56, P = 0.28; DM/non-DM: n = 5/10). The incidence rate and risk of developing overall skin cancer, including NMSC, was significantly higher in older adults with DM. Other significant risk factors for older adults with DM were males for NMSC and melanoma, chronic obstructive pulmonary disease for NMSC, and coronary artery disease for melanoma.

Squamous cell carcinoma with aggressive subclinical extension: 5-year retrospective review of diagnostic predictors

BACKGROUND

Squamous cell carcinoma with aggressive subclinical extension (SCC-ASE) is a tumor whose extensive spread becomes revealed during surgery or pathologic review, particularly during Mohs micrographic surgery. Limited clinical awareness of these lesions may result in unanticipated longer surgical times and larger postoperative defects. SCC-ASE-associated clinical risk factors are not well studied.

OBJECTIVE

We sought to evaluate the incidence of and risk factors associated with SCC-ASE.

METHODS

We conducted a retrospective analysis of SCC treated with Mohs micrographic surgery between 2007 and 2012 at a single academic surgical center. SCC-ASE was defined as a lesion requiring at least 3 Mohs stages with a final surgical margin of ≥1 cm.

RESULTS

Of 954 cases studied, 31% were SCC-ASE. In multivariable analysis, sex (P = .001), history of previous nonmelanoma skin cancer (P < .001), Fitzpatrick skin types II and III (P = .004 and <.001, respectively), immunosuppression related to solid organ transplant (P < .001), and cigarette use (P < .001) were significant predictors of SCC-ASE.

LIMITATIONS

Single academic center selection bias, not-controlled for sun exposure differences, no information on medication regimens of solid organ transplant patients, and a small sample size are all limitations of our study.

CONCLUSION

Easily attainable demographic factors, especially immunosuppressed status and cigarette use, can help predict the occurrence of SCC-ASE and thereby optimize surgical planning and patient preparedness.

Introduction to skin cancer

The incidence of skin cancer has been increasing throughout the United States and much of the world. Although the mortality rate of nonmelanoma skin cancer is low, that type of skin cancer accounts for considerable morbidity, including cosmetic and functional impairment. Melanoma, although less common, is a life-threatening malignancy if not detected and treated early. Skin cancer also significantly contributes to the rising costs of health care in the United States. Prevention, early diagnosis, and treatment are critical in helping to reduce the incidence, morbidity, and mortality associated with skin cancer. This article provides an introduction to skin cancer, including the changing incidence, clinical presentation, and summary of treatment and prognosis.

Repellent activity of fractioned compounds from Chamaecyparis nootkatensis essential oil against nymphal Ixodes scapularis (Acari: Ixodidae)

Preliminary repellent activity of 14 natural products isolated from essential oil components extracted from the heartwood of Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach., were evaluated against nymphal Ixodes scapularis Say in a laboratory bioassay and compared with technical grade N,N-diethyl-3-methylbenzamide (deet). Four hours after treatment, nootkatone and valencene-13-ol had repellent concentration (RC)50 values of 0.0458 and 0.0712% (wt:vol), respectively; two additional Alaska yellow cedar compounds, nootkatone 1 --> 10 epoxide and carvacrol had reported RC50 values of 0.0858 and 0.112%, respectively. The observed RC50 value for deet was 0.0728% (wt:vol). Although not statistically significantly more active than deet, the ability of these natural products to repel ticks at relatively low concentrations may represent a potential alternative to synthetic commercial repellents.

Spatiotemporal Bayesian analysis of Lyme disease in New York state, 1990-2000

Mapping ordinarily increases our understanding of nontrivial spatial and temporal heterogeneities in disease rates. However, the large number of parameters required by the corresponding statistical models often complicates detailed analysis. This study investigates the feasibility of a fully Bayesian hierarchical regression approach to the problem and identifies how it outperforms two more popular methods: crude rate estimates (CRE) and empirical Bayes standardization (EBS). In particular, we apply a fully Bayesian approach to the spatiotemporal analysis of Lyme disease incidence in New York state for the period 1990-2000. These results are compared with those obtained by CRE and EBS in Chen et al. (2005). We show that the fully Bayesian regression model not only gives more reliable estimates of disease rates than the other two approaches but also allows for tractable models that can accommodate more numerous sources of variation and unknown parameters.

Expression of dihydrodiol dehydrogenase plays important roles in apoptosis- and drug-resistance of A431 squamous cell carcinoma

BACKGROUND

Dihydrodiol dehydrogenase (DDH) is a member of the aldo-keto reductases superfamily which may be involved in normal detoxification process of environmental mutagenic hazards like polycyclic aromatic hydrocarbons (PAH). Previous clinical studies have demonstrated the over-expression of DDH in various types of cancers, including cutaneous squamous cell carcinoma (SCC), and its correlation with tumor progression and grave prognosis.

OBJECTIVE

To investigate possible mechanisms for DDH's correlation with tumor progression and unfavorable prognosis.

METHODS

DDH expression in SCC A431 cell line was examined by quantitative real-time PCR and immunoblotting. RNA interference (RNAi) by transduction with retroviral vector containing DDH-targeting small interfering RNA was employed to inhibit DDH expression by A431 cells. With DDH expression inhibited or not, sensitivity of A431 cells to UVB-induced apoptosis and cytotoxicity of chemotherapeutic agent bleomycin were then examined and compared.

RESULTS

DDH was found highly expressed by SCC A431 cells, which was barely detectable in other normal or malignant cutaneous cells, including keratinocytes, fibroblast, and basal cell carcinoma cell line. RNAi Inhibition of DDH expression in A431 cells led to increased sensitivity to UVB-induced apoptosis and cytotoxicity of bleomycin treatment.

CONCLUSION

DDH may play important roles in tumor progression of SCC via induction of apoptosis- and drug-resistance.

Control of immature Ixodes scapularis (Acari: Ixodidae) on rodent reservoirs of Borrelia burgdorferi in a residential community of southeastern Connecticut

A 3-yr community-based study was conducted on residential properties on Mason's Island, Mystic, CT, to determine the efficacy of a rodent-targeted acaricide (fipronil) to control immature Ixodes scapularis (Say) on Peromyscus leucopus. Results indicated that modified commercial bait boxes were effective as an acaricide delivery method for reducing nymphal and larval tick infestations on white-footed mice by 68 and 84%, respectively. Passive application of fipronil significantly reduced the infection rate of Borrelia burgdorferi among white-footed mice by 53%. Moreover, the abundance of questing I. scapularis adults on treated properties was reduced by 77% and fewer were infected with spirochetes (31%) compared with untreated sites (47%) after 3 yr of treatment. Likewise, the abundance of host-seeking nymphs was significantly reduced on treated properties by >50%. Finally, infection rates in flagged nymphal ticks for both B. burgdorferi and Anaplasma phagocytophilum were reduced by 67 and 64%, respectively, after only 2 yr of treatment. Results from this 3-yr trial indicate that the use of fipronil passively applied to reservoir animals by bait boxes is an environmentally acceptable means to control ticks, interrupt the natural disease transmission cycle, and reduce the risk of Lyme disease for residents of treated properties.

Surgical option for nonmelanoma skin cancer

BACKGROUND

Basal cell carcinoma (BCC) is one of the most frequent malignancies in the general population. Its best treatment option is the complete excision of the lesion. Mohs' micrographic surgery has demonstrated to be the surgical method with the highest cure rates, however, it is not available in many countries or institutions.

METHODS

We propose, as a treatment option for high-risk BCC, surgical resection of the tumor with transoperatory histological examination with the hematoxilin-eosin technique, delaying closure of the wounds until the margins and surgical bed are tumor-free.

RESULTS

We studied 83 patients with BCC; 49 were treated with the transoperatory technique and delay closure. We observed no recurrence in any patient that we followed up and there were no complications resulting from the technique in a 25-month follow up.

CONCLUSIONS

We recommend this technique for tumors with high-risk of recurrence if Mohs' micrographic surgery is not available.

An analysis of spirochete load, strain, and pathology in a model of tick-transmitted Lyme borreliosis

Four laboratory-grown, low-passage isolates of Borrelia burgdorferi sensu stricto, B31, JD-1, 910255, and N40, were incorporated into Ixodes scapularis ticks to examine the pathogenesis of these isolates in mice after tick transmission. All isolates induced multifocal, lymphoid nodular cystitis, subacute, multifocal, necrotizing myocarditis, and a localized periostitis and arthritis of the femorotibial joint 6-18 weeks after tick infestation. In terms of the number of mice that demonstrated pathology in bladder, heart, and joint, the highest incidence of lesions occurred 12 weeks after tick bite. Utilizing the Taqman quantitative polymerase chain reaction (q-PCR) fluorogenic detection technology to amplify a conserved region of the flagellin gene, a trend was demonstrated between the number of spirochetes in tissue with duration of pathology. The q-PCR assay developed for this study was sensitive and could reliably measure as few as 1 to 10 spirochetes in the target tissues tested. A higher percentage of B31- and N40-infected mice (92 and 100%, respectively) developed myocarditis than JD-1- or 910255-infected mice (67 and 46%, respectively) 12 weeks after tick bite. The amount of spirochetal DNA that could be amplified for heart at this time point was not statistically different between isolates, indicating a difference in virulence between B31 and N40 relative to JD-1 and 910225. N40-infected mice demonstrated a significantly higher spirochete load (an average of 1.23 spirochetes/mg of tissue, p = 0.045) in femorotibial joints 18 weeks after infection, with 60% of these mice maintaining lesions compared with those infected with B31 (13%), JD-1 (25%), or 910255 (50%), which averaged <0.5 spirochetes/mg of tissue. This mouse model of Lyme borreliosis, including the ability to monitor lesion development and spirochete load, can facilitate the testing of therapeutic regimens for the later stages of tick-transmitted Lyme disease and help investigate aspects of the immunopathogenesis of lesion development.

Protection against lyme disease spirochete transmission provided by prompt removal of nymphal Ixodes scapularis (Acari: Ixodidae)

Public health recommendations for Lyme disease prevention generally include daily tick checks and prompt removal of attached ticks as a means of decreasing the risk of acquiring Lyme disease in highly endemic regions. In the current study, we determined whether crushing nymphal ticks during removal with forceps increased the risk of B. burgdorferi transmission, what degree of protection from transmission of B. burgdorferi was provided by removal of nymphal Ixodes scapularis Say at specific intervals, and whether commercial devices marketed for tick removal worked when tested against nymphal I. scapularis. Both removal via gentle pressure (26% transmission) or crushing the tick (30% transmission) caused a significant decrease in transmission as compared with the sham control (70% transmission). The degree of protection provided via tick removal decreased steadily up to 60 h of attachment; between 60 and 66 h, a dramatic falloff in protection occurred to the point where no protection was observed at 66 h. Finally, commercial tick removal devices varied widely in their efficacy for the removal of attached nymphal I. scapudaris.

Intraepidermal carcinoma of the eyelid

PURPOSE

To examine the clinical and pathological features and treatment outcomes of cutaneous squamous intraepidermal carcinoma of the eyelid in order to determine its behaviour, its relationship to squamous cell carcinoma and appropriate management.

METHODS

All patients from the practice of one of the authors with a histological diagnosis of squamous intraepidermal carcinoma were included. Retrospective chart review was performed, and pathology re-examined. All patients were recalled for examination. Histological diagnosis of periocular intraepidermal carcinoma, lesion characteristics, outcome of surgical excision, local recurrence, and occurrence of metastasis were assessed as main outcome measures.

RESULTS

Thirty-one white, usually fair-haired patients had a total of 37 lesions. Most had a history of occupational or recreational sun exposure. Other predisposing factors included exposure to arsenic, petroleum by-products and epidermodysplasia verruciformis. All except one had other solar keratoses and non-melanoma skin cancers. All had surgical excision. Six cases (16%) had evidence of progression to squamous cell carcinoma. Seven cases (18%) had local recurrence successfully treated by further local excision. No patient had perineural spread or distant metastasis.

CONCLUSIONS

This lesion, which serves as a marker for severe actinic damage, may masquerade as chronic blepharitis. Early diagnosis prior to dermal invasion is important. Complete excision is the recommended treatment. Adjunctive treatment with topical 5-fluorouracil may be appropriate in some circumstances. Long-term follow up is mandatory.

Efficacy of an amitraz-impregnated collar in preventing transmission of Borrelia burgdorferi by adult Ixodes scapularis to dogs

OBJECTIVE

To determine whether an amitraz-impregnated collar could prevent transmission of Borrelia burgdorferi by Ixodes scapularis to dogs.

DESIGN

Laboratory trial.

ANIMALS

8 specific-pathogen-free Beagles.

PROCEDURE

On days -15 and -1, all dogs had negative ELISA results for serum antibodies against B. burgdorferi. On day 0, 4 dogs were each fitted with an amitraz-impregnated (9%) collar, and 4 dogs served as untreated controls. On day 7, all dogs were infested with 100/scapularis (approx 50 females and 50 males) with a known B. burgdorferi infectivity rate of 39.4%. On days 21, 28, 35, 42, 56, 70, and 84, each dog was tested for serum antibodies against B. burgdorferi via ELISA and a western blot technique. Additional ELISA were also performed for serum antibodies against antigenically similar organisms.

RESULTS

By day 70, all control dogs had developed serum ELISA responses ranging from 328 to 510 kinetics-ELISA units (equivalent to end-point titers of approx 43,500 to 60,000), whereas treated dogs remained seronegative throughout the study. Western blot assays performed on all serum samples confirmed that antibodies detected in control dogs reflected responses to specific antigens of B. burgdorferi, whereas treated dogs had no such antibodies. Additional serologic analyses confirmed that antibody responses observed in control dogs were not attributable to antigenically similar organisms.

CONCLUSIONS AND CLINICAL RELEVANCE

Amitraz-impregnated collars prevented transmission of B. burgdorferi in 4 of 4 treated dogs and may be a useful management tool for prevention of borreliosis in dogs.

Ixodes scapularis (Acari: Ixodidae): abundance and rate of infection with Borrelia burgdorferi in four state parks in Wisconsin

Four state parks located in Lyme disease endemic regions of Wisconsin were surveyed for the presence of Ixodes scapularis Say during May and June of 1998 by drag sampling along hiking trails. Nymphal abundance varied between parks, with the average number of nymphs encountered in 1 h ranging from 6.2 +/- 3.8-47.1 +/- 36.3 (mean +/- SD). Questing nymphs were tested for the presence of Borrelia burgdorferi by culture in BSK medium and 7-12% was found to be infected. The average risk of encountering an infected nymph (entomologic risk index) ranged from 0.5 to 5.2 infected nymphs per hour. The highest entomological risk index was recorded from a small island park in northwestern Wisconsin during the last week in May (8.0 infected nymphs per hour). These results indicate a lower risk for human Lyme disease exposure in Wisconsin state parks in comparison with highly endemic areas of the northeastern United States.

Vector competence of Ixodes muris (Acari: Ixodidae) for Borrelia burgdorferi

The vector competence of Ixodes muris (Bishopp & Smith) was determined for Borrelia burgdorferi, the etiologic agent of Lyme disease. Larval I. muris were fed on ICR outbred mice infected with the B-31 laboratory strain of B. burgdorferi. Replete larvae, at 5 d after feeding, were assayed for infection by culture in Barbour-Stoner-Kelly (BSK-H) media. Infection frequency in I. muris replete larvae was 66%. Resultant nymphs were fed on naive ICR outbred mice to determine the ability of I. muris to transmit infection. Infection frequency in fed nymphs declined to 38% and only 1/5 mice was positive for B. burgdorferi on ear biopsy culture. We demonstrated that I. muris is capable of acquiring and transmitting B. burgdorferi but is a relatively poor vector compared with I. scapularis (Say).

Feasibility of controlling Ixodes scapularis ticks (Acari: Ixodidae), the vector of Lyme disease, by parasitoid augmentation

A theoretical analysis of the feasibility of controlling tick populations (Ixodidae) by the release of reared Ixodiphagus parasitoids in tick ecosystems yielded promising results. The analysis suggested that if reasonable progress could be made in mass-rearing the parasitoids, it would be possible to control the blacklegged tick, Ixodes scapularis (Say), the vector of Lyme disease, by this biological control procedure. Lyme disease has become the most important vector-borne disease in the United States. In a field-release experiment conducted in Africa by members of the International Center for Insect Physiology and Ecology, effective control of Amblyomma variegatum (F.) was obtained by the release of Ixodiphagus parasitoids in tick habitats. Encouraging theoretical results along with the encouraging results of a field-release experiment indicate the need for civil and political leaders in countries where ticks are a major problem to sponsor strong and well-coordinated research initiatives focused on the development of this new method of dealing with tick problems.

The cost effectiveness of vaccinating against Lyme disease

To determine the cost effectiveness of vaccinating against Lyme disease, we used a decision tree to examine the impact on society of six key components. The main measure of outcome was the cost per case averted. Assuming a 0.80 probability of diagnosing and treating early Lyme disease, a 0.005 probability of contracting Lyme disease, and a vaccination cost of $50 per year, the mean cost of vaccination per case averted was $4,466. When we increased the probability of contracting Lyme disease to 0.03 and the cost of vaccination to $100 per year, the mean net savings per case averted was $3,377. Since few communities have average annual incidences of Lyme disease >0. 005, economic benefits will be greatest when vaccination is used on the basis of individual risk, specifically, in persons whose probability of contracting Lyme disease is >0.01.