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Background Kaposi sarcoma (KS) is a mesenchymal tumor with distinct histopathological features according to tumor progression. Programmed death-1 (PD-1) and its ligand PD-L1 play major roles in the immune escape strategy of tumors. Objectives This study evaluated expression of PD-1 and PD-L1 in various stages of KS and investigated associations between their expression and clinical characteristics. Methods Fifty cases with histopathologically diagnosed KS were classified as early or late stage. These specimens were stained with anti-PD-1 and anti-PD-L1 antibodies. The extent of expression in the intratumoral and peri-tumoral areas was judged by two dermatopathologists. Results PD-1 and PD-L1 were expressed in 72.2% (13/18) and 11.1% (2/18) of early-stage cases, respectively, compared with 43.8% (14/32) and 28.1% (9/32) of late-stage cases, respectively. At the late stage, PD-1 expression was significantly higher in the peri-tumoral area than in the intratumoral area (P = 0.001). PD-1 expression in the intratumoral area was significantly higher at the early stage than at the late stage (P = 0.013). PD-L1 expression in the peri-tumoral area was significantly higher at the late stage than at the early stage (P = 0.038). Conclusions The pattern of PD-1 and PD-L1 expression differs according to the stage of KS, but is unaffected by clinical variables.

Background Few studies have evaluated the histopathologic features of cutaneous extranodal natural killer (NK)/T-cell lymphoma (ENKTL), and the histopathologic spectrum of this disease according to its clinical morphology remains unclear. Objective This study investigated the differences in pathologic findings of cutaneous ENKTL depending on clinical morphology. Methods A total of 41 cases of cutaneous ENKTL were included. Skin lesions were classified according to clinical morphology as: (i) nodular lesions, (ii) cellulitis or abscess-like swellings and (iii) erythematous to purpuric patches. Histopathologic variables were compared between groups. Results Perivascular infiltration of tumor cells and vasculopathy in the dermis and subcutaneous layer were common microscopic findings irrespective of clinical morphology. Erythematous to purpuric patches were mainly composed of small-sized tumor cells, whereas medium- to large-tumor cells were predominant in lesions of other clinical morphologies. The density of tumor cell infiltration was significantly higher in cellulitis or abscess-like lesions or nodular lesions compared with erythematous to purpuric patches. A panniculitis-like pattern and angiocentricity were less common in patch lesions than in cellulitis-like swelling and nodular lesions. Conclusion There is a histopathologic spectrum of cutaneous ENKTL that is dependent on the clinical morphology.

Few studies have evaluated the histopathologic features of cutaneous extranodal natural killer (NK)/T-cell lymphoma (ENKTL), and the histopathologic spectrum of this disease according to its clinical morphology remains unclear.This study investigated the differences in pathologic findings of cutaneous ENKTL depending on clinical morphology.A total of 41 cases of cutaneous ENKTL were included. Skin lesions were classified according to clinical morphology as: (i) nodular lesions, (ii) cellulitis or abscess-like swellings and (iii) erythematous to purpuric patches. Histopathologic variables were compared between groups.Perivascular infiltration of tumor cells and vasculopathy in the dermis and subcutaneous layer were common microscopic findings irrespective of clinical morphology. Erythematous to purpuric patches were mainly composed of small-sized tumor cells, whereas medium- to large-tumor cells were predominant in lesions of other clinical morphologies. The density of tumor cell infiltration was significantly higher in cellulitis or abscess-like lesions or nodular lesions compared with erythematous to purpuric patches. A panniculitis-like pattern and angiocentricity were less common in patch lesions than in cellulitis-like swelling and nodular lesions.There is a histopathologic spectrum of cutaneous ENKTL that is dependent on the clinical morphology.

Angiomyxolipoma (vascular myxolipoma) is a recently described rare variant of lipoma, four cases of which have been reported to date. Microscopically, the lesion consists of adipose tissue without lipoblasts, extensive myxoid areas, and numerous blood vessels. The main differential diagnosis of this lesion is myxoid liposarcoma, and other adipocytic lesions such as myxolipoma, myxoid spindle cell lipoma should be included. We report two cases of angiomyxolipoma located in the subcutaneous tissue of the forearm and the wrist.

Background: Epithelioid sarcoma is a rare mesenchymal neoplasm. Recently, a more aggressive, so-called ‘proximal type’ epithelioid sarcoma has been described. Clinical case: A 40-year-old-woman presented with 5 × 4 cm, erythematous, indurated, non-movable, painful mass on the pubic area. Histopathology demonstrated diffuse tumor-cell infiltration into the subcutaneous and fascia, which was consisted of prominent epithelioid cells and scattered rhabdoid cells. A multinodular growth pattern or granulomatous appearance with central necrosis was not observed. The tumor cells showed positive reactions for vimentin, cytokeratin (AE1/AE3), and CD34. Despite the surgery, left inguinal mass with lymphadenopathy occurred one month later. We also carried out comparative genomic hybridization (CGH) with tumor cells. CGH revealed chromosomal gain of 5q32-qter, 12q24-qter, and 22q. Conclusion: We report a case of proximal-type of epithelioid sarcoma, which showed the chromosomal gains of 5q32-qter, 12q24-qter, and 22q by CGH.

Eccrine angiomatous hamartoma (EAH) is a rare, benign condition characterized histologically by increased numbers of eccrine elements, as well as numerous capillary channels. In most cases, EAH arises as a single lesion; however, multiple variants have been reported. We report a 35-year-old female patient with multiple, sudoriparous, subcutaneous nodules on the right foot, which showed typical histopathological findings of EAH, and vascular components of the tumor consisted of thin-walled dilated vascular spaces intermixed with spindle cells and some histiocytoid endothelial cells representing spindle cell hemangioma (SCH). To our knowledge, the co-existence of EAH with SCH is a novel finding and not yet described.

Myoepithelioma is a rare but well-characterized group of tumours, among which myoepithelioma of the salivary glands is the best known. We report two patients with myoepithelioma of parotid gland presenting as infra-auricular subcutaneous mass. The lesions were clinically suspected to be epidermal cyst. The biopsies revealed that most of the tumour cells showed epithelioid features with oval or spindle eosinophilic cytoplasm. No ductal or syringomatous epithelial structures were observed. The tumour cells showed cytoplasmic immunoexpressions of vimentin, cytokeratin (AE1/AE3), S-100 protein and smooth muscle actin (SMA). In one patient, a strong calponin positivity was observed. Maguetic resonance imaging (MRI) of both patients revealed exophytic, well-defined, strongly enhancing mass in superficial lobe of parotid gland, confirming the parotid gland origin. Myoepithelioma of parotid gland can be presented as a slowly growing tumour of pre- or infra-auricular area. In dermatologic department, it can be misdiagnosed as various dermal or subcutaneous tumours.

Epithelioid sarcoma is a rare mesenchymal neoplasm. Recently, a more aggressive, so-called "proximal type" epithelioid sarcoma has been described.A 40-year-old-woman presented with 5 x 4 cm, erythematous, indurated, non-movable, painful mass on the pubic area. Histopathology demonstrated diffuse tumor-cell infiltration into the subcutaneous and fascia, which was consisted of prominent epithelioid cells and scattered rhabdoid cells. A multinodular growth pattern or granulomatous appearance with central necrosis was not observed. The tumor cells showed positive reactions for vimentin, cytokeratin (AE1/AE3), and CD34. Despite the surgery, left inguinal mass with lymphadenopathy occurred one month later. We also carried out comparative genomic hybridization (CGH) with tumor cells. CGH revealed chromosomal gain of 5q32-qter, 12q24-qter, and 22q.We report a case of proximal-type of epithelioid sarcoma, which showed the chromosomal gains of 5q32-qter, 12q24-qter, and 22q by CGH.