Fibroma-like PEComa: a newly recognized soft tissue neoplasm in tuberous sclerosis patients-imaging features and review of literature.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of spindled to epithelioid cells that co-express both melanocytic and myogenic markers. Recently, in 2018, a distinctive variant of PEComa has been described that arises in association with tuberous sclerosis complex (TSC) and resembles a fibroma by conventional morphology (called fibroma-like PEComa). Herein, we describe a case of a fibroma-like PEComa in a 4-year-old male child with a known diagnosis of tuberous sclerosis who presented with a firm mass along the anteromedial aspect of the right knee. The mass was excised, and microscopic examination showed bland spindled to stellate cells embedded in a dense collagenous stroma, morphologically resembling a fibroma. Immunohistochemistry analysis showed positivity for desmin (a myogenic marker) and HMB45 (a melanocytic marker), a hallmark for PEComas. To our knowledge, only six cases of fibroma-like PEComa have been described in the literature so far and this is the first report of such a tumor in the medial retinaculum of the knee joint with illustrations of conventional and diffusion imaging features. This case highlights the unique association of fibroma-like PEComa lesions with TSC. This should be considered a differential diagnosis for T2 hypointense masses in tuberous sclerosis patients. In addition, a diagnosis of fibroma-like PEComa should prompt further evaluation for associated TSC.

How Long Is Too Long? Trials and Tribulations of an Indolent Tumor.

A 31-year-old African American man presented for workup of a right hilar and tracheal mass. Stability of the mass when compared with a computed tomographic scan performed 3 years prior suggested an indolent process. On bronchoscopy, there were 2 separate although morphologically similar endobronchial lesions, one in the distal trachea and the second at the level of the right upper lobe bronchus. Biopsies of both lesions demonstrated granular cell tumors. Subsequent rigid bronchoscopy with ablation led to resolution of wheeze, decrease in dyspnea, and documented improvements in both ventilation and perfusion to the right lung. This case illustrates both a rare disease (multifocal endobronchial granular cell tumor) and the physiological impact of reducing large airway obstruction.

Diffuse infiltrative neurofibroma: a clinical, radiological, and histological conundrum.

Diffuse infiltrative neurofibroma is a rare clinical entity that can pose a diagnostic challenge not only due to its rarity but also due to its varied clinical, radiological, and histological features. Our case illustrates how this entity may be misdiagnosed on clinical and pathological examination. Radiological imaging plays a critical and collaborative role in guiding clinicians and pathologists when faced with this challenging diagnosis.

Leiomyosarcoma of the urinary bladder: a clinicopathological study of 34 cases.

BACKGROUND: Leiomyosarcomas of the urinary bladder (LMS-UB) are rare, usually aggressive neoplasms. Owing to their rarity, only a limited number of cases with clinical follow-up information have been published. There is no current consensus on LMS-UB grading, and it is unknown whether the widely accepted Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) and National Cancer Institute (NCI) grading systems of soft-tissue sarcomas are applicable to LMS-UB. METHODS: The authors studied 34 well-characterised LMS-UB and compared the prognostic power of the FNCLCC and NCI systems with that of one published grading scheme for LMS-UB (Mayo). All available slides from 34 LMS-UB were retrieved and evaluated with regards to degree of differentiation, mitotic rate/10 high-powered fields (HPF), and % necrosis. Cases were graded using published criteria for the FNCLCC, NCI and Mayo schemes. Follow-up information was obtained. RESULTS: The tumours occurred in 17 females and 17 males, ranging from 31 to 91 years (median 65), and measured 2-12 cm in size. One tumour was well differentiated, 17 tumours were moderately differentiated, and 16 tumours were poorly differentiated. Mitotic rates ranged from 1 to >30/10 HPF (median 12/10 HPF), and tumours showed 0-60% necrosis (median 25%). FNCLCC grades were 1 (3), 2 (12) and 3 (19). NCI grades were 1 (2), 2 (11) and 3 (21). Mayo grades were low (7) and high (27). FNCLCC and NCI grades were identical in 23/34 cases (68%). Four cases were FNCLCC/NCI grade 2 or 3 and Mayo low-grade. Clinical follow-up was available for 25 of 34 patients (74%). Clinical follow-up of > or =12 months was available for 17 of these 25 cases (68%) with a median follow-up duration of 52 months (range 12-120 months). Adverse outcome was seen in nine of these 17 patients (53%). Seven of the eight cases (88%) with a clinical follow-up duration of <12 months died of their disease. Overall, adverse outcome was documented in 16 of 25 (64%) cases. Metastatic disease was seen in 13 of 25 (52%) cases, with the lungs being the most common site of metastasis (62%). Adverse outcome was noted in 15 of 23 (65%) of FNCLCC grade 2 or 3 LMS-UB, as compared with zero of two (0%) FNCLCC grade 1 tumours (p=0.15), in 15 of 23 (65%) NCI grade 2 or 3 LMS-UB, versus zero of two (0%) NCI grade 1 sarcomas (p=0.17) and in 13 of 20 (65%) Mayo high grade LMS-UB, as opposed to two of five (40%) low-grade lesions (all results not statistically significant). CONCLUSIONS: The authors conclude that LMS-UB occurs in older adults of either sex and is characterised by aggressive behaviour, with adverse outcome in >60% of cases. Certain advantages of the FNCLCC system may support its more widespread adoption for future studies.