Search PubMed⌕ Search

Biomedical subjects

J K Koh

Publications and source records attributed to J K Koh.

At least 91 records · Page 5Linked to original sources

Cellular neurothekeoma with possible neuroendocrine differentiation.

We report a case of cellular neurothekeoma showing unusual immunohistochemical findings and occurring on the left upper arm of a healthy 48-year-old woman. She presented with a 1 cm, red, asymptomatic, dermal nodule of 1 year duration. A biopsy showed dermal proliferation of plexiform fascicles of spindle-shaped or polygonal cells with plentiful eosinophilic cytoplasms. The immunohistochemical profile included negative stains for S-100, CD34, factor XIIIa, CD68, HMB45, cytokeratins, and EMA, strongly positive stains for neuron specific enolase (NSE), synaptophysin, and chromogranin A, and focally positive ones for NKI/C3 and alpha-smooth muscle actin. Ultrastructural analysis showed undifferentiated mesenchymal cells with cytoplasmic projections and abundant RER. Although we couldn't find any confirmative cell type in this cellular tumor, we believe that cellular neurothekeoma is predominantly composed of undifferentiated cells that can exhibit features of neuroendocrine cells in addition to fibroblastic or myofibroblastic ones, suggesting a divergent cell origin.

Biopsy, Needle↗

Juvenile chronic myelogenous leukemia, neurofibromatosis 1, and xanthoma.

The triple association of leukemia, xanthomatous skin lesions, and neurofibromatosis 1 (NF) was first described by Royer et al. in 1958. Most of the leukemias were of the juvenile chronic myelogenous type (JCML). We describe a 7-year-old male child with xanthoma, neurofibromatosis 1, and juvenile chronic myelogenous leukemia. His mother also had NF1. We suggest that the presence of xanthomas and NF1 in a young child should raise awareness of the possible development of JCML, especially in patients with a family history of NF1.

Bone Marrow↗

Subcutaneous emphysema with spontaneous pneumomediastinum and pneumothorax in adult dermatomyositis.

We describe a 32-year-old patient with adult dermatomyositis who developed dyspnea and worsening of pre-existing infarcted skin lesions of the fingers. Chest radiographs showed diffuse hazy reticulonodular infiltration in both lungs, subcutaneous emphysema, pneumomediastinum, and pneumothorax. The pulmonary symptoms and cutaneous lesions gradually improved with a high dose of prednisolone. Although subcutaneous emphysema and pneumomediastinum occur frequently in association with traumatic disruption of cutaneous and mucosal barriers and assisted ventilation, it has rarely been observed in patients with interstitial pneumonitis in connective tissue diseases. Although dermatomyositis and subcutaneous emphysema are all relatively well-known diseases to dermatologists, the occurrence of spontaneous pneumomediastinum and pneumothorax and subsequent subcutaneous emphysema in connective tissue diseases such as dermatomyositis is unfamiliar. We discuss the possible mechanisms of this condition.

Adult↗

Congenital CD34-positive granular cell dendrocytosis.

Granular cell tumors involving the skin are mostly acquired lesions. The Schwann cell origin of these lesions is supported by positive immunostaining for S-100 protein and myelin basic protein. S-100- granular cell lesions rarely have been described in association with fibrous papules or dermatofibromas. The congenital variety of S-100- granular cell tumors occurs almost exclusively in the gingiva. The cell origin of these lesions is not well delineated. We report a hitherto undescribed case of a congenital cutaneous lesion which is histologically characterized by diffuse dermal infiltrates of S-100- but CD34+ granular dermal dendrocytes. The granular appearance of these CD34+ dendrocytes is attributed to an abundance of phagolysosomes. The pathogenetic mechanism of this unusual lesion remains to be elucidated.

Antigens, CD34↗

Extramammary Paget's disease with aggressive behavior: a report of two cases.

Extramammary Paget's disease (EMPD) is an intraepithelial neoplastic disorder which is included as a rare malignant condition. However, it sometimes shows aggressive behavior of local recurrence and coexisting malignancy. We had experienced nine cases of EMPD involving the scrotum for seven years. Two cases of them presented metastasis. The first case presented extensive inguinal lymph node metastasis with underlying adnexal adenocarcinoma one year after wide local excision. The second case initially presented multiple metastasis to the liver and in the lymph node. The latter, showing fulminant progression with liver metastasis, may be only the second case reported in English literature. EMPD is considered as a malignant neoplasm with aggressive behavior from initial presentation. Because wide local excision of the lesion alone may be occasionally insufficient, a careful follow-up must be done to detect recurrence or internal malignancy.

Aged↗

The potential role for CDC42 protein from rat brain cytosol in phospholipase D activation.

Phospholipase D (PLD) has been extracted from rat brain membranes and chromatographically enriched 70-fold. From the rat brain cytosol, Cdc42 with a Mr of about 24,000 and ADP-ribosylation Factor (Arf) with a Mr of about 18,000 have been purified to near homogeneity. PLD was activated better by purified cytosolic Arf than by the other small G proteins tested. Cdc42 purified from rat brain cytosol showed 70% of PLD activation activity exerted by cytosolic Arf, suggesting that Cdc42 may be one of the major G proteins involved in the activation of membrane-associated PLD. While Cdc42 or RhoA exhibited synergistic activation of PLD when administered in conjunction with Arf, Cdc42 and RhoA showed an additive effect when used together. It is possible that Arf and Rho family proteins may have different interaction sites on PLD. These findings support a role for GTP-binding proteins of the Rho family as well as Arf in the activation of membrane-associated PLD and further suggest that Cdc42 may be a major G protein involved in the PLD activation in rat brain.

Amino Acid Sequence↗

Four cases of pustulotic arthro-osteitis.

We describe four cases of pustulotic arthro-osteitis. All of them suffered from anterior chest wall symptoms, such as swelling and pain on the sternoclavicular joint, sternal angle area, sternocostal joint, and costochondral junction. Although chest X-ray findings were all normal, 99mTc-scintigraphy revealed increased uptake in the affected areas in all cases. Laboratory examinations including rheumatoid factor were negative or normal except for elevation of the erythrocyte sedimentation rate and C-reactive protein in 2 cases. After treatment with non-steroidal anti-inflammatory drugs and etretinate or topical PUVA, the skin lesions on the palms and soles and the arthro-osteitis were moderately improved. Pustulotic arthro-osteitis should be considered when a patient with pustulosis palmoplantaris complains of anterior chest wall pain and other joint pain.

Adult↗

Diagnostic pitfalls of Merkel cell carcinoma and dramatic response to chemotherapy.

Merkel cell carcinoma (MCC) is an unusual malignant tumor that arises from neuroendocrine cells with features of epithelial differentiation. We describe a MCC patient with unusual clinical, histopathological, and immunohistochemical features. Although the microscopic, immunohistochemical, and ultrastructural characteristics of MCC have been well defined, diagnostic difficulties remain, particularly in distinguishing it from lymphoma involving the skin, as suggested by our case. This is an unusual case in which dense lymphoid infiltration masked the true tumor. All the immunohistochemical markers of MCC except neuron-specific enolase (NSE) were negative. The dramatic response to primary chemotherapy was also very noteworthy.

Adult↗

Cutaneous mesenchymal hamartoma on the foot.

We report a 16-year-old man with a cutaneous mesenchymal hamartoma on the left foot since infancy. Clinically, the lesion was 10x6 cm in size, relatively ill-defined, skin colored, and comprised of confluent nodules. Histopathologic examination revealed histology compatible with cutaneous mesenchymal hamartoma.

Adipocytes↗

Eosinophilic pustular folliculitis (Ofuji's disease) in myelodysplastic syndrome.

We describe a case of eosinophilic pustular folliculitis (EPF, Ofuji's disease) in a 12-year-old male who suffered from myelodysplastic syndrome. Bone marrow study revealed an increase in the eosinophil cell line without peripheral blood eosinophilia in our case. We suggest that the immunologic abberations ascribed to myelodysplastic syndrome and the increase in the eosinophil cell line in the bone marrow might play roles in the development of EPF in our case.

Adrenal Cortex Hormones↗

Successful removal of traumatic tattoos in Asian skin with a Q-switched alexandrite laser.

BACKGROUND: Traumatic tattoos result from mechanical penetration of the skin by foreign-body particles associated with puncture, abrasive, or explosive trauma. Until the recent development of the Q-switched lasers, it was not possible to remove tattoo pigments without scar and pigmentary changes. OBJECTIVE: The objective of this study was to determine the effectiveness of the Q-switched alexandrite laser (wavelength, 755 nm; pulsewidth, 100 ns), in treating the 27 cases of Asian skin with 36 traumatic tattoos and to observe any side effects such as scarring or pigmentary change. METHODS: The results of treatments on 16 patients with 19 penetrant tattoos, 10 patients with 16 abrasive tattoos and 1 patient with bomb explosion were clinically analyzed. RESULTS: Greater than 76% removal of tattooed pigments required an average of 1.7 treatment sessions in penetrant tattoos in contrast with 2.4 sessions in abrasive tattoos. The excellent removal of traumatic tattoos required 7.5 J/cm2 except the scarred region of one explosive tattoo and one abrasive tattoo on soil. There were no permanent side effects such as scar or permanent pigmentary changes. CONCLUSION: In conclusion, the Q-switched alexandrite laser is a safe and highly effective modality for removal of various traumatic tattoos without scar or permanent pigmentary change in Asian skin.

Adolescent↗

Two cases of linear focal elastosis (elastotic striae).

Linear focal elastosis (LFE) or elastotic striae was first described by Burket in 1989 in three elderly men. They presented with striae-like yellow palpable bands on their backs. Burket described many fine wavy bundles of elastic fibers separating the collagen in the middle to reticular dermis under microscopic examination. Until recently, there have been about 14 reported cases of LFE; elderly males are predominant. We encountered two Korean teen-aged males with linear, reddish, palpable bands and some atrophic bands across their backs. Histopathological examination revealed that elastosis was not as prominent as in previously reported cases. Our cases might represent early-evolving LFE.

Adolescent↗

Neuroleptic drugs alter the dopamine transporter-mediated uptake and release of dopamine: a possible mechanism for drug-induced tardive dyskinesia.

A bovine dopamine transporter (bDAT) cDNA was transfected into CV-1 cells, a cell line that lacks vesicular storage and release mechanisms. Using this cell line, the effects of neuroleptic drugs on DAT-mediated uptake and release of dopamine (DA) were examined. All of the neuroleptic drugs tested, inhibited DA uptakes in DAT expressing cells, and most of them were shown to promote spontaneous release of DA at the same time. These results imply that neuroleptic drugs would cause an overflow of DA in the synaptic cleft of extrapyramidal dopaminergic neurons, which could be one of the possible mechanisms of drug-induced tardive dyskinesia.

Animals↗

A case of hidroacanthoma simplex.

There are many conditions characterized by nests of cells within the epidermis. One of them, hidroacanthoma simplex, has been regarded as an epidermal tumor differentiating to intraepidermal eccrine duct cell. We report a case of hidroacanthoma simplex with the results of immunohistochemical study. Staining for 35 beta H11 (reacting with keratin No. 8), 35 beta E12 (reacting with keratin No. 1, 5, 10, 11), S-100 protein, and CEA was negative in the tumor cell nests; these monoclonal antibodies stained the nests of eccrine poroma.

Acrospiroma↗

Species differences in functions of dopamine transporter: paucity of MPP+ uptake and cocaine binding in bovine dopamine transporter.

Expression of cloned cDNA for human, rat and bovine dopamine transporter (DAT) in COS cells allows the comparison of the functional differences among the respective dopamine transporters. Human DAT showed the highest activities for dopamine uptake, MPP+ uptake and cocaine binding, indicating that humans are more vulnerable to 1-methyl-4-phenylpyridinium (MPP+) toxicity and cocaine addiction. However, bovine DAT showed poor MPP+ uptake and cocaine binding, even though its dopamine uptake ability was quite avid. Here, we conclude that the paucity of MPP+ uptake and cocaine binding is a unique characteristic in bovine DAT.

1-Methyl-4-phenylpyridinium↗