Immunohistochemistry in diagnostic dermatopathology

CD93 Ameliorates Diabetic Wounds by Promoting Angiogenesis via the p38MAPK/MK2/HSP27 Axis

OBJECTIVE

Diabetic wounds are a complication of diabetes mellitus, which is characterised by microcirculation dysfunction caused by decreased local blood supply and insufficient metabolic exchange. Clinically, in addition to glycaemic control, the most important treatment for diabetic wounds is to promote local angiogenesis, which accelerates wound healing. The authors previous study demonstrated that CD93, which is specifically expressed on vascular endothelial cells (ECs), redundantly regulates angiogenesis in zebrafish, suggesting that CD93 is a potential angiogenic molecule. However, the role of CD93 in diabetic wounds has not yet been elucidated.

METHODS

The angiogenic effects of CD93 were studied from four aspects: exogenous, endogenous, in vitro, and in vivo. CD93 recombinant protein was used in microvascular ECs and in mice to observe angiogenesis in vitro and in vivo. The wound model was established in CD93-/- and wild type diabetic mice, and the degree of wound healing as well as the amount and maturity of neovascularisation were investigated. The possible mechanism of CD93 in angiogenesis was determined by CD93 overexpression in cultured ECs.

RESULTS

CD93 recombinant protein was found to exogenously promote tube formation and sprouting of ECs. It also recruited cells to promote the formation of vascular like structures in subcutaneous tissue and accelerated wound healing by optimising angiogenesis and re-epithelisation. Furthermore, CD93 deficiency was observed to delay wound repair, characterised by reduced neovascularisation, vascular maturity, and re-epithelisation level. Mechanically, CD93 activated the p38MAPK/MK2/HSP27 signalling pathway, positively affecting the angiogenic functions of ECs.

CONCLUSION

This study demonstrated that CD93 promotes angiogenesis both in vitro and in vivo and that its angiogenic role in vitro is mediated by the p38MAPK/MK2/HSP27 signalling pathway. It was also found that CD93 exerts beneficial effects on wound healing in diabetic mice by promoting angiogenesis and re-epithelisation.

Antibody-Based Targeted Interventions for the Diagnosis and Treatment of Skin Cancers

BACKGROUND

Cutaneous malignancies most commonly arise from skin epidermal cells. These cancers may rapidly progress from benign to a metastatic phase. Surgical resection represents the gold standard therapeutic treatment of non-metastatic skin cancer while chemo- and/or radiotherapy are often used against metastatic tumors. However, these therapeutic treatments are limited by the development of resistance and toxic side effects, resulting from the passive accumulation of cytotoxic drugs within healthy cells.

OBJECTIVE

This review aims to elucidate how the use of monoclonal Antibodies (mAbs) targeting specific Tumor Associated Antigens (TAAs) is paving the way to improved treatment. These mAbs are used as therapeutic or diagnostic carriers that can specifically deliver cytotoxic molecules, fluorophores or radiolabels to cancer cells that overexpress specific target antigens.

RESULTS

mAbs raised against TAAs are widely in use for e.g. differential diagnosis, prognosis and therapy of skin cancers. Antibody-Drug Conjugates (ADCs) particularly show remarkable potential. The safest ADCs reported to date use non-toxic photo-activatable Photosensitizers (PSs), allowing targeted Photodynamic Therapy (PDT) resulting in targeted delivery of PS into cancer cells and selective killing after light activation without harming the normal cell population. The use of near-infrared-emitting PSs enables both diagnostic and therapeutic applications upon light activation at the specific wavelengths.

CONCLUSION

Antibody-based approaches are presenting an array of opportunities to complement and improve current methods employed for skin cancer diagnosis and treatment.

Current state of melanoma diagnosis and treatment

Melanoma is the deadliest form of skin cancer. In the early stages, melanoma can be treated successfully with surgery alone and survival rates are high, but after metastasis survival rates drop significantly. Therefore, early and correct diagnosis is key for ensuring patients have the best possible prognosis. Melanoma misdiagnosis accounts for more pathology and dermatology malpractice claims than any cancer other than breast cancer, as an early misdiagnosis can significantly reduce a patient's chances of survival. As far as treatment for metastatic melanoma goes, there have been several new drugs developed over the last 10 years that have greatly improved the prognosis of patients with metastatic melanoma, however, a majority of patients do not show a lasting response to these treatments. Thus, new biomarkers and drug targets are needed to improve the accuracy of melanoma diagnosis and treatment. This article will discuss the major advancements of melanoma diagnosis and treatment from antiquity to the present day.

Immunohistochemistry: relevance in dermatology

Use of immunohistochemical technique is increasing in diagnosing various diseases. In many situations it may not be possible to differentiate entities with overlapping clinical and histopathological features. Immunostaining of cellular antigens is immensely helpful in such cases. Immunohistochemistry (IHC) has also been in use for targeted cancer therapy. In this article, the discussion will be restricted to use of IHC in dermatological disorders and use of classical antigens with brief updating of some important newly discovered antigens.

The keratin-14 expression in actinic keratosis and squamous cell carcinoma: is this a prognostic factor for tumor progression?

PURPOSE

Actinic keratosis (AK) is an incipient form of cutaneous squamous cell carcinoma (SCC). We determined if the pattern of expression of keratin-14 (K14) is a factor for tumor progression in AK and SCC.

MATERIALS AND METHODS

Eighteen sections from the tissues of 16 patients were stained with anti-K14 antibody and p16(INK4a). Among the 16 patients, 4 were diagnosed with both SCC and AK at the same site, but AK developed first and SCC developed subsequently. Thus, SCC may have evolved from AK. The other 12 patients were only diagnosed with AK.

RESULTS

In all of the AK and SCC tissues, basement membranes showed positive staining for K14. However, strong reactivities were shown in the spinous and granular layers and focuses of dermal invasion in the SCC tissues developed from AK. Two and 3 of the 12 AK cases had moderately positive reactions for K14 in the spinous and granular layers, respectively. Also, all SCC tissues except one had moderate-to-strong reactions in the basal, spinous, and granular layers for p16(INK4a). Two of the 12 AK cases had weak-to-moderate positive reactions in the basal, spinous, and horny layers for p16(INK4a).

CONCLUSION

The results of our study advance our understanding of the pathogenesis of SCC developing from AK. The results also indicate a differential role in the control of K14 in normal epithelia, AK, and SCC. K14 expression in the spinous and granular layers may be a prognostic factor for tumor progression of AK.

Diagnosis of Mycosis Fungoides

Mycosis fungoides (MF) is the most common form of primary cutaneous T-cell lymphoma. In its early stage it may mimic benign dermatoses both on a clinical and histologic basis. MF usually expresses CD3 and CD4 (T-cell) markers. CD7 is expressed on about 90% of CD4 T cells and is often deficient on malignant T cells. Thus, CD7 may be useful in evaluating the nature of dermal lymphoid infiltrates. The aim of this study was to evaluate the usefulness of immunohistochemical detection of T-cell markers on paraffin-embedded sections, CD3 and CD7 (clone CBC.37), in the differential diagnosis of MF and benign dermatoses. Forty-two patients with diffuse dermal T-lymphocytic infiltrates were selected. Previous clinicopathologic correlation and follow-up had established the diagnosis of MF in 31 patients and benign dermatoses in 11. The mean value of stained cells in MF was 86.45% for CD3 and 53.09% for CD7 (P<0.001); in benign dermatoses it was 79.09% for CD3 and 73.63% for CD7 (P=0.669). CD7 immunolabeling was significantly lower in the MF group (P=0.048). A semiquantitative evaluation revealed a considerable loss of CD7 immunolabeling in comparison with CD3 in patients with MF. The authors conclude that CD7 study may represent a valuable tool in the distinction between inflammation and neoplasia in T-lymphoproliferative skin disorders.

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare idiopathic disease predominately affecting women. The disease is characterized by peribronchial, perivascular, and perilymphatic proliferation of smooth muscle like cells resulting in vascular and airway obstruction and cyst formation. The natural history of pulmonary LAM is unknown, and it displays remarkable diversity in its clinical course. More than 400 citations are currently listed in the literature for LAM. This article reviews and updates the rapidly expanding knowledge about LAM.

Benign metastasizing leiomyoma and lymphangioleiomyomatosis: sex-specific diseases?

The striking similarity between benign metastasizing leiomyoma and lymphangioleiomyomatosis is that they both affect young women. This observation underscores the importance of gender-dependent variables in disease and our lack of understanding of gender differences. Many researchers are currently investigating the link between disease and hormone levels in the body. The beneficial role of estrogens remains in question in pulmonary medicine, and further ongoing research should help to define the role of hormones in the lung.

Reassessment of diagnostic criteria in cutaneous lymphocytic infiltrates

CONTEXT

Non-specific lymphocytic infiltrates of the skin pose difficulties in daily practice in pathology. There is still a lack of pathognomonic signs for the differential diagnosis between benign and malignant lymphocytic infiltrates.

OBJECTIVE

To evaluate the morphological and immunohistochemical profile of lymphocytic infiltrations of the skin according to clinical outcome.

TYPE OF STUDY

Retrospective; histopathological and immunohistochemical analysis.

SETTING

Referral center, university hospital.

SAMPLE

28 cases of lymphocytic infiltrates of difficult differential diagnosis selected from the records.

MAIN MEASUREMENTS

Eighteen histological variables and the immunophenotypic profile were assessed using the CD4, CD8, CD3, CD20 and CD30 lymphoid markers and compared to subsequent follow-up.

RESULTS

The most common diagnoses were: initial mycosis fungoides (eight cases) and drug reactions (five cases). Single morphological variables did not discriminate between benign and malignant infiltrates except for the presence of Pautrier-Darier's microabscesses, which were found only in mycosis fungoides (p = 0.015). Patterns of superficial and deep infiltration (p = 0.037) and also the presence of eosinophils (p = 0.0207) were more frequently found in benign lymphocytic infiltrates. Immunohistochemical profile of T-cell subsets showed overlap between benign and malignant infiltrates with a predominance of CD4-positive (helper) lymphocytes in the majority of cases.

CONCLUSIONS

A combination of clinical and histological features remains the most reliable approach for establishing a definite diagnosis in cases of lymphoid skin infiltrates.

Expression of the ets-1 proto-oncogene in melanocytic lesions

Ets-1 oncoprotein is a transcription factor known to regulate the expression of numerous genes important in extracellular matrix remodeling and angiogenesis. Up-regulation of Ets-1 has been shown to be important in a variety of human malignancies and to correlate with prognosis. To our knowledge, this oncoprotein has not been examined in melanocytic lesions. A series of 10 cutaneous melanomas and 24 benign melanocytic lesions with patient records were independently examined for diagnosis confirmation and immunohistochemical expression by two dermatopathologists. The immunohistochemical expression for Ets-1 (Novocastra, Newcastle upon Tyne, UK) was scored by an average of the mean labeling intensity; no nuclear staining = 0, weak nuclear staining = 1, moderate = 2, and intense = 3. Ets-1 expression was statistically assessed by the one-way analysis of variance (ANOVA) comparing the mean labeling intensity of melanoma to benign melanocytic nevi. All of the benign melanocytic lesions exhibited negative to weak nuclear staining, with an average mean labeling intensity of 0.4. Melanoma in situ exhibited moderate nuclear staining, for a mean labeling intensity of 2.0, whereas all conventional invasive melanomas exhibited moderate to strong nuclear staining, with a mean labeling intensity of 2.7. Metastatic melanoma exhibited very strong nuclear staining, with a mean labeling intensity of 3.0. Invasive desmoplastic melanoma, like melanoma in situ, showed moderate nuclear staining with a mean labeling intensity of 2.1. There was a trend toward more intense staining with melanoma progression. A statistically significant difference in the mean labeling intensity of Ets-1 was seen between invasive melanoma and benign melanocytic nevi (P <.0001). Ets-1 oncoprotein expression, however, does not distinguish among benign melanocytic lesions. Staining intensity and pattern might be a useful adjunct with histomorphology in distinguishing invasive melanoma from benign melanocytic nevi. Furthermore, Ets-1 expression may be an important pathogenic mechanism and predictor of aggressive biologic behavior of cutaneous melanoma, with a trend toward staining intensity increasing as Clark stage increases.

A light microscopic and immunohistochemical evaluation of scars

BACKGROUND

Scars are commonly encountered by dermatopathologists and usually do not present a diagnostic challenge. However, in some cases, the pathologist may need to consider a broad differential diagnosis including fibrohistiocytic tumors, smooth muscle tumors, myofibroblastic proliferations and desmoplastic malignant melanoma. Although specific histologic aspects of scars have been well studied, a complete histochemical profile of scars, especially at various stages of evolution, has not been described.

METHODS

Twenty-five cases of scars including 8 normal scars, 5 hypertrophic scars and 12 keloids were studied. Sections were examined with Verhoeff van Giesson, colloidal iron, Giemsa, smooth muscle actin (SMA), CD34, Factor XIIIa and S-100.

RESULTS

All scars were negative for CD34 expression. Factor XIIIa immunostaining identified only rare dermal dendrocytes. S-100 was absent in 23 of 25 cases and stained scattered cells (less than 10%) in the other 2 cases. SMA was positive in 14 of 25 cases with 6 of these showing staining of up to 50% of spindled cells. Elastic fibers were markedly reduced or absent in all cases, mucin showed moderate or marked staining in three-fourths of the cases and dermal mast cells showed a moderate increase in 5 cases.

CONCLUSIONS

These findings confirm prior reports that negative staining with CD34, Factor XIIIa and S-100 can help differentiate scars from dermatofibrosarcoma protuberans, dermatofibroma and desmoplastic malignant melanoma, respectively. SMA staining is much more variable and requires careful interpretation.

Benign fibrous histiocytoma (BHF) of the cheek: CD 68-KP1 positivity

We present a case of fibrous histiocytoma of the cheek in a 32-year-old male with no evidence of any regional invasion or distant metastasis. Pathologic analysis and diagnosis of these lesions is often challenging, and usually based on a combination of light microscopy and immunohistochemistry. In this study the diagnosis was confirmed using immunostaining with the antibody CD 68-KP1 that is positive in any lesion containing lysosomal granules or phagolysosomes.