Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Darier’s disease is characterized by greasy and scaly papules that primarily affect seborrheic and intertriginous areas which is caused by a mutation in the ATP2A2 gene. Histopathologically, the disease is characterized by acantholysis and dyskeratosis. Among the diverse presentations, the segmental type follows a linear distribution along the lines of Blaschko. Herein, we present a case of a 54-year-old male with generalized erythematous papules that had been linearly distributed across his body for two decades. Lesions on his trunk and extremities were confined to the right side, whereas those on the scalp and face exhibited multiple segmental presentations. Histopathological examination revealed acantholysis and dyskeratosis in the epidermis, confirming the diagnosis of type 1 segmental Darier’s disease. This case underscores the rarity of type 1 segmental Darier’s disease, particularly with multiple segmental involvement and highlights the complexity and variability of this dermatological condition.

Lichen amyloidosis is characterized by coalescent hyperpigmented papules with a predilection for the extremities and is accompanied by severe chronic pruritus. Various therapies have been attempted; however, there is no uniformly recognized effective treatment. In the first case, a 60-year-old man with a 37-year history of intractable itching presented with hyperkeratotic brown papules and coalescing plaques on the trunk and extensor surfaces of the extremities. The second case involved a 31-year-old man who presented with brownish macules and papules with a rippled pattern on the upper back and lower extremities. Histological examination of the lesions from both patients revealed epidermal hyperplasia and amorphous material deposited in the papillary dermis, which tested positive on Congo red staining. Although both patients were diagnosed with lichen amyloidosis, several treatment modalities showed limited efficacy. Subsequently, dupilumab, a treatment for severe pruritus, was administered to both patients, resulting in significant improvements.

A 34-year-old male with acne was presented with a 1-year history of multiple tiny subcutaneous nodules on his face, particularly on both cheeks. Physical examination revealed asymptomatic, palpable, and hard nodules with an acne scar. The skin lesions were more obvious when the cheeks were inflated. A skin biopsy revealed multiple focal bony trabeculae with osteoblasts in the dermis. A diagnosis of multiple miliary osteomas cutis was done. Multiple miliary osteoma cutis is a rare benign extraskeletal ossification that is considered relatively common and under-reported because of its asymptomatic behavior. Osteoma cutis is generally observed in middle-aged females with a history of acne. Male involvement rarely occurs, especially at a young age, as observed in this patient. Topical retinoids were prescribed, but the lesions did not abate at 3 months follow-up.

Traumatic tattoos are abnormal pigmentations caused by embedded foreign particles due to various injuries, including explosions, abrasions, or traffic accidents. Traumatic tattoos caused by pencils are common and considered trivial because they are usually confined to the injured site without any complications. A 4-year-old girl presented with a 5-month history of a grey-to-bluish patch on her left cheek. Histopathological examination revealed many pigment granules surrounding the blood vessels and appendages diffused from the mid to the lower dermis. Various staining methods were employed to verify that colorants caused the tattoo. To our knowledge, there have been no reports of traumatic tattoos caused by colored pencils that spread rapidly beyond the injured areas. In particular, various unexpected traumas can occur frequently in children; therefore, an accurate diagnosis is essential by differentiating it from other acquired pigmentary disorders

Purpose: Emphysematous pyelonephritis (EPN) is a life-threatening disease requiring immediate treatment. This multicenter retrospective cohort study aimed to analyze the mortality rate and risk factors associated with EPN. Materials and Methods: Between January 2011 and February 2021, 217 patients diagnosed with EPN via computed tomography who visited 14 teaching hospitals were retrospectively analyzed. Clinical data, including age, sex, comorbidities, Huang and Tseng classification, hydronephrosis, acute kidney injury, blood and urine tests, surgical interventions, percutaneous drainage, and conservative treatments, were compared between the survival and death groups. Risk factors for mortality due to EPN were analyzed using univariate and multivariate methods. Results: The mean age of survivors and deceased patients was 67.8 and 69.0 years, respectively (p=0.136). The sex distribution (male/female) was 48/146 and 8/15, respectively (p=0.298). Of the 217 patients, 23 died, resulting in a mortality rate of 10.6%. In univariate analysis, the Huang and Tseng classification (p=0.004), platelet count (p=0.005), and acute kidney injury (p=0.007) were significantly associated with mortality from EPN. In multivariate analysis, only the Huang and Tseng classification (p=0.029) was identified as a risk factor. Mortality rates according to the Huang and Tseng classification were as follows: class I (5.88%), class II (7.50%), class IIIa (14.28%), class IIIb (25.00%), and class IV (23.07%). Conclusions EPN is associated with a high mortality rate. Among various clinical factors, the Huang and Tseng classification was the most significant indicator for predicting mortality.

Primary cholangiocarcinoma is a rare bile duct epithelial neoplasm that can present with atypical clinical manifestations, complicating its diagnosis. A 62-year-old male showed symptoms suggestive of a complicated hepatic cyst that was later identified as intrahepatic cholangiocarcinoma. The patient presented with abdominal discomfort without fever. Imaging revealed a large cystic lesion in the liver. Despite the initial treatment for a presumed abscess, a biopsy confirmed cholangiocarcinoma. This case highlights the diagnostic challenge of distinguishing between benign complicated hepatic cysts and malignancies, particularly when typical markers of infection are absent. Early biopsy and vigilant assessments are crucial in such presentations to avoid a delayed diagnosis and initiate appropriate treatment.

Hepatic tuberculosis, typically associated with miliary tuberculosis, can occasionally present as localized liver lesions. This case report describes a 77-year-old male presenting with persistent abdominal pain and fever, following an endoscopic retrograde cholangiopancreatography for bile duct sludge removal. Subsequent computed tomography revealed focal liver lesions. Despite initial treatment with antibiotics for a suspected inflammatory liver abscess, his condition did not improve. A liver biopsy was performed, revealing caseous granulomas, and the tuberculosis polymerase chain reaction result was positive. The patient was diagnosed with primary hepatic tuberculosis, which later disseminated. Oral anti-tuberculosis therapy was initiated and is currently being closely monitored. This case emphasizes the importance of considering hepatic tuberculosis in the differential diagnosis of liver lesions, particularly in cases involving cholestatic liver function tests, and persistent symptoms unresponsive to conventional antibiotics.

Purpose: Emphysematous pyelonephritis (EPN) is a life-threatening disease requiring immediate treatment. This multicenter retrospective cohort study aimed to analyze the mortality rate and risk factors associated with EPN. Materials and Methods: Between January 2011 and February 2021, 217 patients diagnosed with EPN via computed tomography who visited 14 teaching hospitals were retrospectively analyzed. Clinical data, including age, sex, comorbidities, Huang and Tseng classification, hydronephrosis, acute kidney injury, blood and urine tests, surgical interventions, percutaneous drainage, and conservative treatments, were compared between the survival and death groups. Risk factors for mortality due to EPN were analyzed using univariate and multivariate methods. Results: The mean age of survivors and deceased patients was 67.8 and 69.0 years, respectively (p=0.136). The sex distribution (male/female) was 48/146 and 8/15, respectively (p=0.298). Of the 217 patients, 23 died, resulting in a mortality rate of 10.6%. In univariate analysis, the Huang and Tseng classification (p=0.004), platelet count (p=0.005), and acute kidney injury (p=0.007) were significantly associated with mortality from EPN. In multivariate analysis, only the Huang and Tseng classification (p=0.029) was identified as a risk factor. Mortality rates according to the Huang and Tseng classification were as follows: class I (5.88%), class II (7.50%), class IIIa (14.28%), class IIIb (25.00%), and class IV (23.07%). Conclusions EPN is associated with a high mortality rate. Among various clinical factors, the Huang and Tseng classification was the most significant indicator for predicting mortality.