BACKGROUND: It is unknown whether high-frequency ultrasound (HFUS) can evaluate invisible subcutaneous lesions. We aimed to investigate the diagnostic value of HFUS in invisible subcutaneous lesions.
METHODS: Patients with invisible subcutaneous lesions were prospectively recruited from two centres. Before undergoing biopsy or surgery, each lesion was independently evaluated by two clinicians. One provides a clinical diagnosis by only clinical examination and the other provides an integrated diagnosis by combining clinical examination and HFUS information. Diagnoses were classified as correct, wrong, and indeterminate. A total of 391 lesions from 355 patients were enrolled, including 225 epidermoid cysts, 77 lipomas, 25 pilomatrixomas, 21 haemangiomas, 19 dermatofibromas, 11 dermatofibrosarcoma protuberans (DFSP), 7 neurofibromas, and 6 leiomyomas. Using pathological results as the gold standard, diagnostic performance was compared.
RESULTS: The number of correct diagnoses increased from 185 (47.3%) by clinical examination alone to 316 (80.8%) after the addition of HFUS (P < 0.05). Meanwhile, the indeterminate diagnosis rate decreased from 143 (36.6%) to 10 (2.6%). Using HFUS, the accuracy improved significantly for epidermoid cysts (59.6% vs. 86.7%), lipomas (50.6% vs. 94.8%), pilomatrixomas (0% vs. 48.0%), haemangiomas (23.8% vs. 57.1%), and DFSPs (0% vs. 81.8%) (all p < 0.05). However, HFUS did not significantly improve the diagnostic accuracy of dermatofibromas (15.8% vs. 21.1%, p > 0.999), neurofibromas (42.9% vs. 71.4%, p = 0.625), or leiomyomas (16.7% vs. 100%, p = 0.063).
CONCLUSIONS: Combining HFUS and clinical examination can generally improve the diagnostic accuracy and decrease the indeterminacy of invisible subcutaneous lesions, especially epidermoid cysts, lipomas, pilomatrixomas, haemangiomas, and DFSPs. However, for some rare lesions, HFUS cannot provide useful information.

BACKGROUND: Lipomas are the most frequent benign tumor. They have been described as soft, well-defined, slow-growing palpable masses, and classified as deep or superficial.
OBJECTIVE: To present the clinical and ultrasound findings of herniated superficial subcutaneous lipoma (HSL), located in pressure/support areas, not previously described.
METHODS: A seven-year retrospective review was performed. Patients with a preoperative high-resolution ultrasound (HRUS) diagnosis of HSL archived in the computational system and histological study information were selected.
RESULTS: A total of 37 patients (mean age = 46 years) were recruited. The clinical diagnoses were \"lipoma\" or \"suspected lipoma\" in just 46% of the cases. This was three times more frequent in women. Tumors were located mainly in the gluteal (38%) and proximal thigh areas (35%). Clinically, all patients showed small, soft, rounded skin nodules. On HRUS, they appear as lipomatous tumors that protruded, compressed, and thinned the covering dermal layer. The subcutaneous portion was bigger than the herniated part, with an iceberg image.
CONCLUSIONS: HSL in support areas have a special clinical ultrasound presentation, not previously described. It is important to recognize them for a proper diagnosis and treatment, especially because they clinically may present as small superficial lesions; however, they are associated with a larger subcutaneous portion (iceberg image). It is probable that an estrogen influence on the adipose tissue can be suspected because of the female predominance.

OBJECTIVE: To our knowledge, since 2003, there have been 11 reported cases of intravascular natural killer (NK)-cell lymphoma (IVNKL). Herein we describe the 12th case.
METHODS: H&E and Envision immunohistochemical stains as well as in situ hybridization were used to study this disease in combination with review of the literature.
RESULTS: Half of the cases reported to date are from China and Taipei. The clinical manifestation of IVNKL is erythema in the limbs and trunk, although patients\' conditions have varied notably from each other. One-year survival rate is about 40%.
CONCLUSIONS: IVNKL should be distinguished from extranodal NK/T-cell lymphoma (nasal type) and aggressive NK-cell leukemia. These three diseases have a similar phenotype and are all related to Epstein-Barr virus infection. However, the pathogenesis of similarities and differences needs further study. In particular, IVNKL is quite unusual. The treatment of IVNKL is difficult, and the prognosis is poor. Currently, IVNKL is not included in the World Health Organization classification subtypes and has been classified into NK/T-cell lymphoma (nasal type). However, in view of the unique characteristics of this disease, we propose that the diagnosis be independent, since this will facilitate further study of this disease.