Malignant features of minipig melanomas prior to spontaneous regression

In MeLiM minipigs, melanomas develop around birth, can metastasize, and have histopathologic characteristics similar to humans. Interestingly, MeLiM melanomas eventually regress. This favorable outcome raises the question of their malignancy, which we investigated. We clinically followed tens of tumors from onset to first signs of regression. Transcriptome analysis revealed an enrichment of all cancer hallmarks in melanomas, although no activating or suppressing somatic mutation were found in common driver genes. Analysis of tumor cell genomes revealed high mutation rates without UV signature. Canonical proliferative, survival and angiogenic pathways were detected in MeLiM tumor cells all along progression stages. Functionally, we show that MeLiM melanoma cells are capable to grow in immunocompromised mice, with serial passages and for a longer time than in MeLiM pigs. Pigs set in place an immune response during progression with dense infiltration by myeloid cells while melanoma cells are deficient in B2M expression. To conclude, our data on MeLiM melanomas reveal several malignancy characteristics. The combination of these features with the successful spontaneous regression of these tumors make it an outstanding model to study an efficient anti-tumor immune response.

Predicting regression of cervical intraepithelial neoplasia grade 2 in women under 25 years

BACKGROUND

A number of retrospective and prospective studies have documented substantial rates of regression in cervical intraepithelial neoplasia grade 2 lesions in young women. Initial observational management of cervical intraepithelial neoplasia grade 2 is increasingly accepted as appropriate for women under 25 years of age with screen-detected abnormalities and is included in a number of clinical guidelines. However, there has been a paucity of large prospective studies on observational management with strict inclusion criteria. A number of important questions remain, specifically regarding the clinical variables that are associated with the risk of progression or persistence of disease. To investigate these factors and to ensure that young women with cervical intraepithelial neoplasia grade 2 undergoing observational management were being managed in a well-monitored and an appropriately informed fashion, we conducted a large, multicenter prospective study on observational management of cervical intraepithelial neoplasia grade 2 in women under 25 years.

OBJECTIVE

This study aimed to determine the regression rates and clinical, cytologic, and pathologic predictors of regression of cervical intraepithelial neoplasia grade 2 in women under 25 years undergoing observational management over 24 months.

STUDY DESIGN

This study was a multicenter prospective study on observational management of cervical intraepithelial neoplasia grade 2 (ie, repeat colposcopy, cytology, and cervical biopsy every 6 months) for up to 24 months. A total of 615 consenting women under 25 years with newly-diagnosed, biopsy-proven cervical intraepithelial neoplasia grade 2 were recruited (from 2010 to 2016) through 16 hospital-based colposcopy units in New Zealand and Australia.

RESULTS

At completion, 326 women had confirmed regression, 156 had persistent high-grade cervical intraepithelial neoplasia grade 2 or 3 or adenocarcinoma in situ, and 24 had unconfirmed regression (ie, first regression at the 24-month follow-up). A total of 109 women did not complete the protocol (41 because of delayed follow-up, 41 lost to follow-up, 22 elected treatment, 4 refused a biopsy, and 1 died of an unrelated cause). Confirmed regression was observed in 53% (326 of 615) of all women enrolled in the study and, when missing data were imputed, it was estimated that 64% of women (95% confidence interval, 60%-68%) would have experienced regression. Similarly, lesions regressed in 64% (326 of 506) of women who completed the observational protocol. Based on a multivariable analysis, detection of human papillomavirus 16 in a liquid-based cytology sample at the time of initial colposcopy decreased the chance of regression by 31% (risk ratio, 0.69; 95% confidence interval, 0.56-0.86; P<.001). In addition, at initial colposcopy, low-grade or normal colposcopic impression, later year of diagnosis, low-grade or normal cytology, and being a nonsmoker were all independently associated with an increased chance of regression.

CONCLUSION

More than half of women under 25 years with cervical intraepithelial neoplasia grade 2 will regress to cervical intraepithelial neoplasia grade 1 or normal within 24 months without destructive treatment. The absence of human papillomavirus 16 is the most important predictor of regression.

Reporting regression in primary cutaneous melanoma. Part 2: prognosis, evaluation and management

The effect of histological regression on patient prognosis for primary cutaneous melanoma is controversial. Some authors hypothesize that regression indicates a robust systemic immune response and may decrease risk of metastasis. Others argue that histological regression calls into question a T0 diagnosis because there may have been an invasive component of the melanoma that is no longer visible but is still active. The literature to date does not suggest that histological regression is associated with increased risk of positive sentinel lymph node status, metastasis or increased risk of mortality. Thus, the presence of histological regression should not change patient staging, evaluation or management. The criteria used for reporting regression have varied dramatically across studies, and standardized reporting is needed to foster evidence-based practices in the future.

Spontaneous Regression of Primary Thyroid Lymphoma: Two Rarities at the Same Time

Primary thyroid lymphomas are pretty uncommon, and constitute about 5% of the neoplasms of this organ. Spontaneous tumor regression is defined as the total or partial disappearance of a tumor as proven by microscope without treatment or under inadequate treatment. It is estimated to happen in one out of 60,000-100,000 cases. We present a case of primary thyroid lymphoma with spontaneous regression after diagnostic puncture and corroborated with hemithyroidectomy at four months. The patient died after twenty-six months of follow-up because of endocarditis and there was no relapse at any time.

How to radiologically identify a spontaneous regression of sporadic vestibular schwannoma?

Background

The natural history of sporadic vestibular schwannoma is unpredictable, with tumors growing, non-growing and even showing spontaneous regression in some rare cases.

Objective

This retrospective study aims to describe the radiologic signs characterizing and identifying the shrinking vestibular schwannoma.

Methods

Involution was considered to have occurred if tumor size had decreased by 2 mm or more on its largest diameter. All magnetic resonance imaging scans were reviewed for tumor size, internal auditory meatus size, and tumor characteristics. Volumetric measurements were performed on the first and last scan. Audiometric data were collected at the first and last visit.

Results

Fourteen patients with a confirmed spontaneous regression were included, with a mean follow-up of 5 ± 2.6 years. The mean shrinkage rate was 0.9 ± 0.59 mm/year on 2D measurements, and 0.2 ± 0.17 cm³/year on volumetric measurements, with a relative shrinkage of 40 ± 16.9%. Two remarkable radiologic features were observed: First, a festooned aspect, defined by multiple curves in the tumor outline, noticed in 12 cases (86%); second, the appearance of cerebrospinal fluid filling the internal auditory meatus, associated with an enlargement of the internal auditory meatus compared to the contralateral side, and observed in 10 out of 13 cases with internal auditory meatus invasion (77%). Those two aspects were associated in 64% of cases.

Conclusion

These two newly reported radiologic features could help neurosurgeons, oto-neurosurgeons and neuroradiologists to identify a spontaneous vestibular schwannoma involution at first visit. This could allow any treatment to be postponed, monitoring to be more widely spaced, and patients to be reassured.

Spontaneous Regression of Recurrent Undifferentiated Carcinoma of the Endometrium

We herein report a very rare case of spontaneous regression of recurrent undifferentiated carcinoma of the endometrium. An 80-year-old woman had undergone total hysterectomy with bilateral adnexectomy for undifferentiated carcinoma of the endometrium. The cancer recurred locally 10 months after surgery and then metastasized to the lung and liver. After she and her family elected to receive supportive care without active treatment, the local recurrences dramatically decreased, and the metastases of the lung, liver, and peritoneum also disappeared. This case showed that spontaneous regression can occur even with malignant tumors showing an extremely poor prognosis, such as undifferentiated carcinoma of the endometrium.

Multiscale Modeling of Glioblastoma Suggests that the Partial Disruption of Vessel/Cancer Stem Cell Crosstalk Can Promote Tumor Regression Without Increasing Invasiveness

OBJECTIVE

In glioblastoma, the crosstalk between vascular endothelial cells (VECs) and glioma stem cells (GSCs) has been shown to enhance tumor growth. We propose a multiscale mathematical model to study this mechanism, explore tumor growth under various initial and microenvironmental conditions, and investigate the effects of blocking this crosstalk.

METHODS

We develop a hybrid continuum-discrete model of highly organized vascularized tumors. VEC-GSC crosstalk is modeled via vascular endothelial growth factor (VEGF) production by tumor cells and by secretion of soluble factors by VECs that promote GSC self-renewal and proliferation.

RESULTS

VEC-GSC crosstalk increases both tumor size and GSC fraction by enhancing GSC activity and neovascular development. VEGF promotes vessel formation, and larger VEGF sources typically increase vessel numbers, which enhances tumor growth and stabilizes the tumor shape. Increasing the initial GSC fraction has a similar effect. Partially disrupting the crosstalk by blocking VEC secretion of GSC promoters reduces tumor size but does not increase invasiveness, which is in contrast to antiangiogenic therapies, which reduce tumor size but may significantly increase tumor invasiveness.

SIGNIFICANCE

Multiscale modeling supports the targeting of VEC-GSC crosstalk as a promising approach for cancer therapy.

Feedback Regulation in a Cancer Stem Cell Model can Cause an Allee Effect

The exact mechanisms of spontaneous tumor remission or complete response to treatment are phenomena in oncology that are not completely understood. We use a concept from ecology, the Allee effect, to help explain tumor extinction in a model of tumor growth that incorporates feedback regulation of stem cell dynamics, which occurs in many tumor types where certain signaling molecules, such as Wnts, are upregulated. Due to feedback and the Allee effect, a tumor may become extinct spontaneously or after therapy even when the entire tumor has not been eradicated by the end of therapy. We quantify the Allee effect using an 'Allee index' that approximates the area of the basin of attraction for tumor extinction. We show that effectiveness of combination therapy in cancer treatment may occur due to the increased probability that the system will be in the Allee region after combination treatment versus monotherapy. We identify therapies that can attenuate stem cell self-renewal, alter the Allee region and increase its size. We also show that decreased response of tumor cells to growth inhibitors can reduce the size of the Allee region and increase stem cell densities, which may help to explain why this phenomenon is a hallmark of cancer.

Overexpression of p16(INK4a) in Mastocytosis (Urticarial Pigmentosa)

The expression of p16(INK4a) has been reported to induce cell-cycle arrest and cellular senescence. The p16(INK4a) expression has never been examined in human mast cells and mastocytosis. We immunohistologically examined the expression of p16(INK4a) and tryptase in 5 normal human skin and 4 mastocytosis. In normal mast cells, only 5.9 ± 3.4 (mean ± standard deviation) % of tryptase-positive mast cells coexpressed p16(INK4a). However, significantly higher percentage (86.0 ± 14.1%) of tryptase-positive tumor cells was immunoreactive to p16(INK4a) in all of 4 mastocytosis. The p16(INK4a) overexpression may induce the senescence of neoplastic mast cells to undergo spontaneous regression of mastocytosis.

Model-Based Evaluation of Spontaneous Tumor Regression in Pilocytic Astrocytoma

Pilocytic astrocytoma (PA) is the most common brain tumor in children. This tumor is usually benign and has a good prognosis. Total resection is the treatment of choice and will cure the majority of patients. However, often only partial resection is possible due to the location of the tumor. In that case, spontaneous regression, regrowth, or progression to a more aggressive form have been observed. The dependency between the residual tumor size and spontaneous regression is not understood yet. Therefore, the prognosis is largely unpredictable and there is controversy regarding the management of patients for whom complete resection cannot be achieved. Strategies span from pure observation (wait and see) to combinations of surgery, adjuvant chemotherapy, and radiotherapy. Here, we introduce a mathematical model to investigate the growth and progression behavior of PA. In particular, we propose a Markov chain model incorporating cell proliferation and death as well as mutations. Our model analysis shows that the tumor behavior after partial resection is essentially determined by a risk coefficient γ, which can be deduced from epidemiological data about PA. Our results quantitatively predict the regression probability of a partially resected benign PA given the residual tumor size and lead to the hypothesis that this dependency is linear, implying that removing any amount of tumor mass will improve prognosis. This finding stands in contrast to diffuse malignant glioma where an extent of resection threshold has been experimentally shown, below which no benefit for survival is expected. These results have important implications for future therapeutic studies in PA that should include residual tumor volume as a prognostic factor.

Effects of Referral Bias on Estimates of Anal Intraepithelial Neoplasia Progression and Regression Rates in a 3-State Markov Model

The study aim is to compare anal intraepithelial neoplasia (AIN) progression and regression rates in a cytology inception cohort to estimates based on the subcohort referred for ≥1 high-resolution anoscopies (HRAs).A cytology-based retrospective cohort was assembled including the anal cytology histories and invasive anal cancer (IAC) outcomes of all HIV-infected adults under care between 2001 and 2012. A 3-state Markov model (<HSIL↔HSIL→IAC) was estimated separately for all patients and for the subcohort undergoing ≥ 1 HRAs with biopsy. Cytology was adjusted for misclassification. State transition rates (per person-year) and covariate hazard ratios were estimated using the R package msm.Of 2804 eligible patients in the inception cohort, 629 (22%) were in the HRA subcohort and 2175 (78%) in the non-HRA subcohort. Patients in the HRA subcohort were more likely to have baseline CD4<350, viral load >400, and to have HSIL at baseline and thereafter. They also had more anal cytology examinations (median 6 vs 3) and longer follow-up (median 5.5 vs 3.6 years). State transition rates were overestimated in the HRA subcohort relative to inception cohort, but the degree of discordance varied by transition: for <HSIL to HSIL (0.44 vs 0.04); for HSIL to <HSIL (0.56 vs 0.17); and for HSIL to IAC (0.014 vs 0.011). Beneficial covariate effects on the <HSIL to HSIL transition were concordant (P < 0.05) for time-updated HIV viral load, CD4 count, and antiretroviral therapy. The observed effects of HRA-triage bias may be relevant to estimates of AIN state transitions from other cohorts subject to referral bias.

Possible Spontaneous Regression of a Metastatic Lesion of Keratoacanthoma-Like Squamous Cell Carcinoma in a Regional Lymph Node

We report herein a case of keratoacanthoma-like squamous cell carcinoma in an 82-year-old male that showed regional lymph node metastasis followed by self-regression of the metastatic lesion. This case is consistent with the previously reported observation that tumors compatible with the clinical features of keratoacanthoma may have malignant biological potential, however, it also demonstrates that even metastatic lesions may exhibit self-regression similar to that observed for primary lesions. Despite the view that keratoacanthoma-like squamous cell carcinoma may represent a variant of squamous cell carcinoma, occasionally it undergoes a unique clinical course.

Spontaneous regression of breast cancer with axillary lymph node metastasis: a case report and review of literature

Spontaneous regression (SR) of cancer is a rare but well-documented biological phenomenon. However, the mechanism remains to be elucidated. We herein report a case of the SR of breast cancer at both the primary site and metastatic axillary lymph node with spontaneously-induced T cell-mediated immunological responses. A 52-year-old female with a lump in the left axilla was diagnosed to have a small breast carcinoma with a distinct axillary lymph node metastasis. During the preoperative systemic examination, she was diagnosed to have severe type 2 diabetes mellitus, was treated with insulin, and the hyperglycemia was normalized after one month. Surgery for left breast cancer was then performed. The postoperative histopathological examination revealed the SR of breast cancer at both the primary site and metastatic axillary lymph node. Immunohistochemical studies revealed that estrogen receptor positive, AE1/AE3-positive ductal carcinoma completely underwent necrosis associated with extensive infiltration of CD3-positive T cells in the tumor nodule in the lymph node. In addition, primary ductal carcinoma cells also underwent single cell necrosis with infiltration of T cells with lymph follicle-like organization of B cells in the mammary gland. The features were suggestive that the tumor eradication in the metastatic lymph node and regression of the primary ductal carcinoma could be due to host T cell response to the ductal carcinoma. As far as we know it is the first report that shows the spontaneous regression of breast cancer, probably due to the spontaneously-induced T cell response.

Completely regressed primary cutaneous melanoma - difficulties in diagnosis and classification

Complete regression of primary cutaneous melanoma is a very rare phenomenon. Only 49 cases of well-documented completely regressed primary cutaneous melanoma have been reported to date. The clinical picture and histological findings may vary considerably. The presence of regional lymphadenopathy represents a necessary requisite for the diagnosis of completely regressed primary cutaneous melanoma. However, some cases lie outside these criteria and are difficult to diagnose and classify. Moreover, completely regressed melanoma is not specifically referred to in the current AJCC (American Joint Commission on Cancer) melanoma staging system. We report three cases of completely regressed primary cutaneous melanoma. One of the cases presented with unquestionable clinical and histopathological findings of completely regressed primary cutaneous melanoma, but without concomitant regional lymph node metastasis. As expected, this patient eventually developed nodal metastatic disease. An extraordinary case of a completely regressed melanoma that appeared in association with a congenital melanocytic nevus is also documented. This case revealed a unique type of regression that affected only the melanoma. The nevus was left undisturbed by the immunological response.

Spontaneous regression of metastatic melanoma - clinical evidence of the abscopal effect

INTRODUCTION

Metastatic melanoma is poorly understood. Regression of primary lesions has been associated with poor prognosis, but spontaneous regression of all metastatic disease is clearly beneficial. A patient's own immune responses occasionally appear to stimulate spontaneous regression of metastatic disease in melanoma.

PATIENTS AND METHODS

We present six interesting cases of complete or nearly complete spontaneous regression of metastatic melanoma, suggest possible causes and review the literature.

RESULTS AND CONCLUSIONS

These cases show clear radiological, pathological or clinical evidence of spontaneous regression of metastatic melanoma. This remains a poorly understood phenomena warranting further investigation and may prove useful in the development of immune mediated solutions.

[Observation on the growth and metastasis of cross-strain transplanted tumors in different mouse strains]

OBJECTIVE

Mouse tumors were subcutaneously transplanted into different mouse strains and their growth and metastatic properties were checked, to explore the possibility of establishing animal tumor models in different mouse strains other than their normal host strains.

METHODS

Seven mouse tumor cell lines: H22, S180, U14, FC, Ca761, SMG-A and DCS were transplanted into C57BL/6J, ICR or KM mice, and their tumorigenicity, growth and metastasis were recorded and analyzed.

RESULTS

The tumor formation rate of H22 cells in both the C57BL/6J and ICR mice was 100%, but the growth of H22 tumors was significantly faster in the C57BL/6J (2.8 ± 0.4)g than in the ICR mice (1.5 ± 0.5)g at the 17th day after transplantation (P<0.001). The S180 tumors grew stably in C57BL/6J mice and the tumor formation rate was 100%. The U14 inoculated into C57BL/6J and KM mice showed both lymphatic and lung metastasis and formed significantly larger tumors in KM mice [(12.6 ± 3.4)g] than that in the C57BL/6J mice [(10.2 ± 2.2)g] on the 32rd day after transplantation (P = 0.002). Transplantation of FC, Ca761, and SMG-A did not form tumors or the tumors were completely regressed later in C57BL/6J mice. DCS cells formed tumors in C57BL/6J mice, but some of the tumors regressed. The retained tumors were passaged in C57BL/6J mice, and the substrain DCS-C57 cells was established which showed stable growth and had a 100% tumor formation rate and 100% lung metastasis rate in C57BL/6J mice.

CONCLUSIONS

Cross-strain transplanted tumors can be successfully established by inoculation of poorly differentiated and highly malignant tumor cells into different mouse strains. Some highly immunogenic tumor cells may form tumor, however, the tumors are regressed later, and can not establish cross-strain transplanted tumors in other mouse strains. Stable transplanted tumor models can be obtained from the partially regressed tumors after continuous passages in vivo.

Immunohistochemical and immunoelectron study of major histocompatibility complex class-II antigen in canine cutaneous histiocytoma: its relation to tumor regression

In order to investigate the immune mechanisms involved in regression of canine cutaneous histicytoma (CCH), major histocompatibility complex (MHC) class-II immuno-expression and the number of T- and B-lymphocytes and macrophages were analyzed in 93 cases of CCH. MHC class-II was also studied in 16 cases of CCH by immunoelectron microscopy. All tumors expressed MHC class-II, and two major staining patterns were identified: focal juxtanuclear cytoplasmic staining and rim-like staining along the cell periphery. The MHC class-II labelling pattern and T- and B-lymphocyte infiltrates were associated with tumor regression. In regressing lesions, MHC class-II molecules shift to the cell surface and an increase of both T- and B-lymphocytes were noted. The increasing expression of MHC class-II molecules on the cell surface could be a significant factor for the onset and progression of tumour regression.

Spontaneous regression of hepatocellular carcinoma in a cirrhotic patient: possible vascular hypothesis

Spontaneous regression of hepatocellular carcinoma is extremely rare, and the exact pathogenesis leading to this remarkable phenomenon remains unclear. We describe a case of spontaneous regression of an incidentally discovered hepatocellular carcinoma in a 63-year-old man with hepatitis C cirrhosis. The regression followed a series of events, in particular, an upper gastrointestinal haemorrhage. Ischaemic insult may be a major pathway leading to tumour regression. As limited data is available in the literature, knowledge and recognition of this rare event will have implications for patient management and may alter treatment. Further, data may be useful to assess if these patients have an altered prognosis with improved survival.

Spectrum of morphologic alterations of regression in cutaneous melanoma--potential for improving disease prognosis

INTRODUCTION

Regression occurs as a complex interaction between tumor cells and host's immune response; neither biologic mechanisms, nor regression prognostic significance are deciphered to date but promising anti-cancer vaccine strategies were thus developed.

METHODS

We analyzed 127 superficial spreading melanomas identifying melanoma with regression (segmentary (SR), partial (PR) and segmentary & partial (SR-PR)) or without regression (AR). Several histopathologic parameters were registered; statistical analysis was performed (level of significance P < 0.05).

RESULTS

Regression was present in 52% cases, less frequently in pT4 melanomas. Ulceration and vascular invasion were similarly present in pT2-pT4 melanomas with regression and significantly less in pT1 ones; their incidence increased with stage in AR (P < 0.001). SR and SR-PR melanomas showed significantly more tumor infiltrating lymphocytes within the non-regressed tumor than AR melanomas (P < 0.05). SR melanomas presented significantly less frequent mitoses than PR (P = 0.04), SR-PR (P = 0.04) or AR ones (P = 0.03). Marked inflammation and more numerous melanophages were present regressed areas advanced stage melanomas. More numerous plasma cells were identified in advanced stages; in SR and SR-PR melanomas less numerous plasma cells were present in pT1 than in advanced stages. Vascular hyperplasia was significantly higher in SR than SR-PR cases.

CONCLUSIONS

Differences in perception of regression might be the result of labeling with similar name of various processes comprising inflammation and tumor cells destruction; at least in thin melanomas, PR and SR seem to belong to different spectrum of alteration, SR bearing a more favorable potential. Further studies will be performed in order to further elucidate the mechanisms involved in regression in melanoma.

Spontaneous regression of septum pellucidum/forniceal pilocytic astrocytomas--possible role of Cannabis inhalation

INTRODUCTION

Spontaneous regression of pilocytic astrocytoma after incomplete resection is well recognized, especially for cerebellar and optic pathway tumors, and tumors associated with Neurofibromatosis type-1 (NF1). The purpose of this report is to document spontaneous regression of pilocytic astrocytomas of the septum pellucidum and to discuss the possible role of cannabis in promoting regression.

CASE REPORT

We report two children with septum pellucidum/forniceal pilocytic astrocytoma (PA) tumors in the absence of NF-1, who underwent craniotomy and subtotal excision, leaving behind a small residual in each case. During Magnetic Resonance Imaging (MRI) surveillance in the first three years, one case was dormant and the other showed slight increase in size, followed by clear regression of both residual tumors over the following 3-year period. Neither patient received any conventional adjuvant treatment. The tumors regressed over the same period of time that cannabis was consumed via inhalation, raising the possibility that the cannabis played a role in the tumor regression.

CONCLUSION

We advise caution against instituting adjuvant therapy or further aggressive surgery for small residual PAs, especially in eloquent locations, even if there appears to be slight progression, since regression may occur later. Further research may be appropriate to elucidate the increasingly recognized effect of cannabis/cannabinoids on gliomas.

[Spontaneous regression of mucosa-associated lymphoid tissue lymphoma of the lung]

We report a case of mucosa-associated lymphoid tissue (MALT) lymphoma of the lung that regressed spontaneously. An 82-year-old man was referred to our hospital because of an abnormal chest shadow. Chest CT scans showed soft tissue components along the periphery of the left main bronchus. Bronchoscopy showed an edematous and protruding lesion. Pathological findings showed diffuse invasion of small lymphoid cells of B-cell origin in the submucosal layers. These cells formed lymphoepithelial lesions. Southern blot hybridization demonstrated monoclonality and immunoglobulin heavy-chain gene rearrangement. We diagnosed MALT lymphoma of the lung. Spontaneous regression was found clinically 16 days after the first tumor biopsy for diagnosis by bronchoscopy. Autofluorescence imaging (AFI) 8 months after the first biopsy showed a decrease in magenta color. Immunohistochemical staining showed marked decrease in CD20 + B cells and an increase in the proportion of T cells, the majority of which were CD4 + T cells. No relapse of these lesions was detected 20 months after the first visit. It may be possible to closely follow up pulmonary MALT lymphoma without immediate treatment.

Spontaneous regression of thoracic malignancies

BACKGROUND

Clinicians are frequently questioned by patients about the possibility of spontaneous regression of tumors. Although there are many reports and a few case series documenting spontaneous regression, there is concern that these cases may not represent true regression. Using specific criteria, we attempted to determine the incidence and types of thoracic malignancy most likely to regress spontaneously.

METHODS

We used a PubMed search of the phrase "spontaneous regression of thoracic lesions" reported from 1951 to December 2008. Using a modified Everson and Cole criterion we developed to define spontaneous regression, this search was refined for true spontaneous regression of primary and metastatic thoracic malignancies.

RESULTS

Only 5 cases in the literature involved spontaneous regression of a primary thoracic malignancy. These include pleural mesothelioma, primary lung cancer and adenoid cystic carcinoma. 71 cases involved true spontaneous regression of metastatic thoracic neoplasms, of which 5 cases showed regression of the primary extrapulmonary tumors along with the pulmonary metastasis. Thoracic metastasis from renal cell carcinoma was the most common malignancy found to regress spontaneously.

CONCLUSION

Spontaneous regression of primary thoracic malignancy is rare. Renal cell carcinoma accounts for most reported cases.

Pregnancy-related fibroid reduction

We tested the hypothesis that the protective effect of parity on fibroids is due to direct pregnancy-related effects by following women from early pregnancy to postpartum period with ultrasound. Of 171 women with one initial fibroid, 36% had no identifiable fibroid at the time of postpartum ultrasound, and 79% of the remaining fibroids decreased in size.

[Spontaneous regression of hepatocellular carcinomas]

We report a rare case of spontaneous regression (SR) of hepatocellular carcinoma (HCC). A 70-year-old man consulted us for general fatigue. Enhanced abdominal computed tomography (CT) showed two HCCs, of 5cm in the posterior segment and 8cm around the right Glissonean pedicle with tumor thrombus in the main portal trunk. He refused to undergo any treatment, but 28 months later, CT showed complete disappearance of the hilar tumor and portal tumor thrombus, and partial regression in the posterior tumor with shrinkage of the right lobe of the liver. His PIVKA-II levels decreased from 23358 to 217mAU/ml. In the present case, tumor infarction of the portal thrombus, and the administration of imidapuril hydrochloride and Hochu-ekki-to may have caused SR.

Spontaneous regression of metastatic Merkel cell carcinoma

Merkel cell carcinoma is a rare aggressive neuroendocrine carcinoma of the skin predominantly affecting elderly Caucasians. It has a high rate of local recurrence and regional lymph node metastases. It is associated with a poor prognosis. Complete spontaneous regression of Merkel cell carcinoma has been reported but is a poorly understood phenomenon. Here we present a case of complete spontaneous regression of metastatic Merkel cell carcinoma demonstrating a markedly different pattern of events from those previously published.

Spontaneous regression of human cancer cells in vitro: potential role of disruption of Cdk1/Cdk4 co-expression

BACKGROUND

Although well-acknowledged in vivo, spontaneous death of cancer cells in vitro is less widely appreciated.

MATERIALS AND METHODS

Colony formation was studied in untreated control plates of standard clonogenic assays and measurements of actual and potential doubling times performed in asynchronous cultures of human cancer cells lines. Western blotting of lung large cell carcinoma, COR-L23 cells actively undergoing spontaneous cell death was also carried out.

RESULTS

Catastrophic disintegration of mature colonies could be seen in the untreated plates of lung large cell carcinoma, H460 and colon adenocarcinoma, SW620 human cancer cell lines and a significant cell loss factor was present in the cell lines growing as adherent cells in continuous culture. Western blotting demonstrated alterations of relative cyclin dependent kinase (Cdk)1 to Cdk4 protein expression in dying COR-L23 cells.

CONCLUSION

The phenomenon of spontaneous cell death should be considered a hallmark of cancer and may be the result of failure to stabilise unstable, fully developed cancer cells due to the disruption of Cdk1/Cdk4 co-expression in those cells.

Congenital epulis: an unusual case of spontaneous regression

Congenital epulis is a rare benign neoplasm of the soft tissues. Typically, this condition manifests as a firm, smooth, pink mass that appears exclusively on the alveolar ridges in newborn infants. Surgical excision usually is recommended; however, smaller lesions may disappear spontaneously over time. This article reports an unusual case of a girl whose dentist diagnosed congenital epulis when she was 16 months old; the epulis disappeared completely three months later. Diagnostic and prognostic issues and treatment options are discussed.

[Regression in malignant melanoma. Definition, etiopathogenesis, morphology and differential diagnosis]

Malignant melanoma is a neoplasm that more often tends to undergo regression. Clinically, variation in color is perhaps the most important hallmark of primary cutaneous melanoma. The change in color to white, off-white, blue-white and gray-white is a sign of (spontaneous) regression in malignant melanoma. Histopathologically the process starts with a dense lichenoid infiltrate of lymphocytes, and ends with fibrosis and/or melanosis within a thickened papillary dermis. The dense infiltrate of lymphocytes permeates the thin melanoma and destroys the atypical melanocytes in the epidermis and the papillary dermis. A key concern is how to define regression in a reproducible way. Using the following definition, a statistically significant risk of metastases can be demonstrated in thin melanomas (<1.0 mm) with extensive regression (>50%): "fibroplasia with an absence of epidermal and dermal involvement by melanoma cells, but allowing for (lentiginous) single-cell proliferation of atypical melanocytes along the dermo-epidermal junction".

The correlation of regression in primary melanoma with sentinel lymph node status

BACKGROUND

The significance of regression in primary melanoma has been disputed for many years. Some have suggested regression as a marker for poor prognosis while others have reported a negligible or even a favourable effect, on prognosis.

AIM

To understand the significance of regression in melanoma and provide further information on whether patients should be subjected to sentinel lymph node biopsy (SLNB) on the basis of regression.

METHODS

146 melanoma cases who had undergone SLNB were included in the study. The histological criteria for offering SLNB were melanoma >1 mm in thickness, Clark's level IV or those with regression.

RESULTS

A statistically significant greater proportion of individuals without regression showed sentinel lymph node (SLN) positivity (p = 0.028) compared with those which do show regression. Metastatic disease correlated with growth phase of the primary lesion. All the node positive cases were in the vertical growth phase; none of the cases in radial growth phase and showing regression were associated with nodal metastasis (p = 0.029). 62 cases had melanomas with thickness <1 mm and were in radial growth phase, yet were offered SLNB because of regression. Of these, 44 showed features of regression and all were node negative. The remaining 16 cases of thin melanomas did not show regression; 2 of these had sentinel node metastasis.

CONCLUSION

Results suggest that regression is usually a favourable process, particularly in thin melanomas and that metastasis in "thin melanomas showing regression" is real but rare. Variant vertical growth phase, mitoses and other prognostically significant variables may be more important predictors of metastatic potential in thin melanomas.

Absence de valeur prédictive des signes de régression histologique sur l’envahissement du ganglion sentinelle

BACKGROUND

The predictive value of regression in melanoma is debated.

AIM OF THE STUDY

A retrospective single-centre study to evaluate the correlation between regression in primary skin tumor and the presence of micrometastases in sentinel lymph nodes.

PATIENTS AND METHODS

Histological signs of regression in 84 melanomas (>1 mm) with corresponding sentinel lymph nodes were studied by two independent pathologists.

RESULTS

Regression was seen in 40 skin melanoma tumors while micrometastasis was seen in 24. Of the tumors with micrometastasis, only 10 were regressive (RR: 0.47, p=0.49). Breslow value>2 mm and male sex were predictive for node micrometastasis (RR: 4.6, p=0.03 and RR: 7.6, p=0.006, respectively). On multivariate analysis, these two factors were independent.

COMMENTS

These data suggest that regression in primary cutaneous melanoma is not predictive for lymph node metastasis.

[Histopathological prognostic factors of malignant melanoma]

The incidence of melanocytic skin lesions, including malignant melanoma has increased in the past few years; histopathologists and dermatopathologists have to face them more often. The correct treatment of melanoma patients by the oncodermatologist and oncologist is based on the histopathological report containing the most important histological prognostic factors. However, the accurate interpretation of these factors may be difficult in the everyday practice, especially in reporting tumor thickness, the level of invasion, the type of exulceration and regression. It is important to standardize the content of the histopathological reports in a reproducible way.

Unusual findings in papillary thyroid microcarcinoma suggesting partial regression: a study of two cases

Histologic changes of regression have been recognized in many malignant tumors, although they have not been documented in thyroid carcinoma. We analyze here the histologic features of 2 cases of papillary thyroid microcarcinoma, one of the diffuse sclerosing variant and another multicentric of the follicular variant, that suggest partial regression. The histologic and clinical features of the 2 thyroid microcarcinomas were compared with the features of regression reported in other tumors. Hematoxylin and eosin stains were examined in each case. In addition, immunoperoxidase stains for thyroglobulin and thyroid transcription factor-1 were performed on the metastatic and primary lesions of each case. Immunostains for CD4 and CD8 performed on the thyroid lesions were also examined. Both patients presented with metastatic papillary thyroid carcinoma in regional lymph nodes with no clinical or radiologic evidence of primary tumor in the thyroid glands. When examined, the thyroid glands revealed only microscopic foci of papillary thyroid carcinoma measuring less than 1.5 mm, diffuse sclerosis and a lymphocytic infiltrate mainly composed of cytotoxic T lymphocytes around the neoplastic microfollicles. Numerous psammoma bodies were also found in the thyroid of case 1, and venulitis similar to that seen in acute hepatic rejection was also seen in the microcarcinoma of case 2. The 2 patients reported had papillary thyroid microcarcinomas measuring less than 1.5 mm and features suggestive of regression characterized by extensive fibrosis, an accompanying T lymphocyte infiltrate, venulitis, and only a few clusters of neoplastic cells or a few neoplastic follicles. Thus, we believe that these histologic changes suggest regression because papillary thyroid microcarcinomas measuring less than 1.5 mm do not metastasize and have been considered innocuous or medical curiosities.

Regression of Atypical Nevus: An Anecdotal Dermoscopic Observation

BACKGROUND

Clark nevi (atypical melanocytic nevi) can be considered as risk markers and potential precursors of melanoma. The authors report on the morphologic changes of an atypical nevus by dermoscopic follow-up examination over a 7-year period.

CASE REPORT

A 43-year-old man had a brown macule on his back, sized 5 mm, with an irregular shape, clinically and dermoscopically diagnosed as an equivocal melanocytic lesion. Dermoscopically during the initial examination, a predominant reticular pattern with peripheral eccentric hyperpigmentation in the lower portion of the lesion could be seen. After 7 months, the area of peripheral eccentric hyperpigmentation had regressed, and after 4.5 years the atypical pigment network had almost disappeared. After 7 years of follow-up, a diffuse area of hypopigmentation and a residual light brown pigmentation were detectable. The histopathologic diagnosis was consistent with an atypical junctional nevus with regression with features of a Clark nevus.

CONCLUSION

Based on our observation, even a dermoscopically atypical nevus may undergo regression as documented by long-term dermoscopic follow-up.

Differences in the frequency and function of HHV8-specific CD8 T cells between asymptomatic HHV8 infection and Kaposi sarcoma

It is unclear how the immune response controls human herpesvirus 8 (HHV8; also known as Kaposi sarcoma-associated herpesvirus [KSHV]) replication and thereby prevents Kaposi sarcoma (KS). We compared CD8 T-cell responses to HHV8 latent (K12) and lytic (glycoprotein B, ORF6, ORF61, and ORF65) antigens in patients who spontaneously controlled the infection and in patients with posttransplantation, AIDS-related, or classical KS. We found that anti-HHV8 responses were frequent, diverse, and strongly differentiated toward an effector phenotype in patients who controlled the infection. Conversely, HHV8-specific CD8 cells were very rare in patients who progressed to KS, and were not recruited to the tumoral tissue, as visualized by in situ tetramer staining of KS biopsies. Last, HHV8-specific CD8 T cells were observed in a seronegative recipient of an HHV8infected graft who remained persistently aviremic and antibody negative, suggesting that specific cytotoxic T lymphocytes (CTLs) may provide protection from persistent HHV8 infection. These results support the crucial role of cellular immune responses in controlling HHV8 replication, in preventing malignancies in latently infected subjects, and in conferring genuine resistance to persistent infection. They may also have important implications for the design of prophylactic and therapeutic HHV8 vaccines, and for adoptive immunotherapy of KS.

Spontaneous regression of intraoral mucosa-associated lymphoid tissue lymphoma: molecular study of a case

Mucosa-associated lymphoid tissue (MALT) lymphoma presentation in the oral cavity is very rare. Reported herein is a case of intraoral MALT lymphoma of the minor salivary gland in a 70-year-old woman with Sjogren's syndrome. Unexpectedly, a spontaneous clinically and histologically confirmed regression occurred 1 month after the tumor biopsy for diagnosis. Considering that salivary MALT lymphoma is associated with Sjogren's syndrome and that the chronic inflammation caused by Sjogren's syndrome persisted, it is hypothesized that the tumor clone might be present in the regressed lesion. Minimal residual tumor clone identical with the primary lesion was detected using the polymerase chain reaction (PCR) clonality assay for immunoglobulin heavy chain gene (IgH) rearrangement. No recurrence was clinically evident 38 months after the diagnosis. Spontaneous regression of MALT lymphoma should be examined at the molecular level in addition to clinical and histological evaluations. When minimal residual disease is detected, close follow up is necessary for early detection of the tumor relapse.

The regression of a canine Langerhans cell tumour is associated with increased expression of IL-2, TNF-alpha, IFN-gamma and iNOS mRNA

Canine cutaneous histiocytoma is a benign epidermal neoplasm of Langerhans cell origin, which usually displays spontaneous regression. Based on the degree of lymphocytic infiltration, 30 histiocytomas were classified into four groups representing different stages of tumour regression. To elucidate further the mechanisms of the antitumour immune response CD3+, CD21+, CD4+, CD8+ and myeloid/histiocyte antigen+ inflammatory cells were differentiated by immunohistochemistry and quantified. In addition, the number of apoptotic cells was detected using the TdT-mediated biotin-dUTP nick-end labelling (TUNEL) method. Furthermore, the expression of interleukin- (IL-2), IL-12(p40), tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-10 and transforming growth factor-beta (TGF-beta) as well as inducible nitric oxid synthase (iNOS) mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). Phenotyping of inflammatory cells revealed a significantly increased infiltration of all lymphocyte subsets and myeloid/histiocytic cells with the onset of tumour regression. The latter was significantly correlated to up-regulation of IL-2, TNF-alpha, IFN-gamma and iNOS mRNA expression. Expression of remaining cytokines and percentage of apoptotic cells showed no group-specific changes. The results indicate an initial infiltration of CD4+ T cells followed by increased expression of Th1 cytokines and recruitment of antitumour effector cells as the principal mechanism for tumour regression. Canine cutaneous histiocytoma is a unique example for an effective immune response in a naturally occurring neoplasm derived from epidermal Langerhans cells and might represent a valuable animal model to investigate tumour immunity.

Canine Transmissible Venereal Tumour: Asessment of Mast Cell Numbers as Indicators of the Growth Phase

Mast cells are immune cells that are involved mainly in type 1 hypersensitivity reactions, and they have been implicated in tumour angiogenesis. In this study we assessed the presence of mast cell numbers and microvessel density during the progression and regression stages of natural spontaneous canine transmissible venereal tumours (CTVT). Mast cells were demonstrated by histochemical staining with toluidine blue, alcian blue and safranin O. Microvessel counts were demonstrated by immunohistochemical labelling with an antibody against the endothelial cell marker factor VIII. Mitotic cells, apoptotic cells and tumour infiltrating lymphocytes were counted from haematoxylin-eosin-stained sections. Tumour fibrosis was evaluated on Masson's trichome-stained sections. The results showed that progressing tumours had significantly higher mast cell counts and microvessel counts at the invasive edges of the tumours than did regressing tumours. In both the progressing and regressing tumours, microvessel counts were significantly positively correlated with mast cell counts. Regressing tumours had significantly higher mast cell counts of the whole tumour than progressing tumours. The results also showed that progressing tumours had significantly higher mitotic rate than regressing tumours, and fibrosis and apoptosis were significantly higher in regressing tumours than progressing tumours. There were no significant differences between the biochemical and haematological values of dogs with progressing and regressing tumours. These results suggests that mast cells play a role in CTVT progression probably by promoting vascularization at the invasion front during the progression phase, and that mast cell count could be used as one of the histological factors to indicate growth stage of CTVT.

Spontaneous Regression of Testicular Germ Cell Tumors

Spontaneous regression of testicular germ cell tumors (GCTs) is a well-recognized phenomenon but has been incompletely characterized. Many pathologists are not familiar with the findings that support a diagnosis of a "burnt-out" primary in a patient with metastatic GCT. We therefore report the clinical, gross, and histologic findings in 42 cases of testicular GCT that showed either complete (26) or greater than 50% scarring (16). Thirty-seven patients (88%) had either known GCT metastasis or some residual testicular GCT, and none had treatment before orchiectomy. The patients were 17 to 67 years old, with a median of 32. Thirty presented with symptoms of metastasis, 7 with a testicular mass, 2 with elevated human chronic gonadotropin, and 1 with testicular pain. In 2 patients the presentation was unknown. Two patients had prior orchiopexy; another had an intraabdominal testis, and 2 others had prior contralateral seminoma (20 and 42 years previously). Gross descriptions in 37 cases identified white to tan scars, 0.6 to 2.4 cm, in 33. These were circumscribed in 16, with 15 of these having nodular or multinodular configurations and 1 a band-like appearance. In 9 cases the scar was ill defined or stellate, and in 8 cases no further details concerning the scar configuration were available. In 4 cases no scar was apparent; 2 of these had received intraoperative biopsy. Microscopically, all cases showed circumscribed to irregular foci of scarring, distinct from the adjacent parenchyma, in association with widespread testicular atrophy. Other common features were lymphoplasmacytic infiltrates in the scars (37/42) and "ghost" tubules in scars (31/42). Less common features in the scars included angiomatous foci (22/42), siderophages (15/42), and coarse intratubular calcifications (6/42); in the surrounding testis they included intratubular germ cell neoplasia, unclassified (IGCNU) (22/42), Leydig cell prominence (18/42), and necrosis (5/42). Tubular microliths occurred in 13 cases, 12 peripheral to the scar and 1 within it. Metastases in 31 cases were: pure seminoma (17, 3 with residual testicular seminoma), mixed GCT with seminoma (4, 3 with residual testicular seminoma), mixed nonseminomatous GCT (4, 3 with residual testicular GCT), pure embryonal carcinoma (2), pure teratoma (2, 1 with residual testicular teratoma), and pure yolk sac tumor (2). In 5 cases with clinically diagnosed metastases, there was no histologic documentation of the nature of the metastatic tumor. Testicular tumors in the remaining 6 cases having residual primaries without concomitant metastases were pure seminoma (3), mixed GCT with seminoma (2), and pure embryonal carcinoma (1). The most specific histologic findings of a regressed GCT are a distinct scar in association with either IGCNU or coarse intratubular calcifications; however, many cases lack the latter 2 features. In such cases additional features supportive of regressed GCT include testicular atrophy, microlithiasis and, in the scar, lymphoplasmacytic infiltrates and prominent vascularity. Ghost tubules in many scars are not evidence of a non-neoplastic process but likely reflect regression of tumors with intertubular growth. Intertubular growth is a common finding in seminoma, which is the single most frequent type of regressed GCT, occurring either in pure or mixed form in the metastases of 68% (21/31) of the cases and identifiable in 62% (10/16) of persistent testicular tumors. We conclude that regression of testicular GCTs shows a distinctive constellation of findings that usually permits its recognition. In contrast, nonspecific atrophy lacks distinct scars, and scars from non-neoplastic causes lack most of the associated findings seen in our cases.

Spontaneously relapsing and remitting primary CNS lymphoma in an immunocompetent 45-year-old man

A 45-year-old immunocompetent man with primary central nervous system lymphoma (PCNSL) presented with multiple spontaneous relapses and remissions in the absence of steroid treatment. Because of the fluctuations with improvement in both the clinical course and MRI findings, alternative disorders were considered that led to delay of diagnosis and treatment prior to brain biopsy. This case and a handful of others with single remissions emphasize that PCNSL cannot be reliably ruled out by improving or disappearing symptoms, signs or traditional MR imaging abnormalities.