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Pulmonary contusion (PC), defined as damage to the lung parenchyma with edema and hemorrhage, has classically been associated with acceleration-deceleration injuries. It is a frequent pathology in clinical practice. However, its clinical presentation and imaging findings are nonspecific. Patients with this entity can present with findings that can range from mild dyspnea to life-threatening respiratory failure and hemodynamic instability. We present the case of a 61-year-old man, a former smoker, who presented to the emergency department after suffering blunt chest trauma. On admission, he complained of only mild shortness of breath, and his vital signs were typical. Initial imaging identified asymmetric pulmonary infiltrates and mediastinal lymphadenopathy; this was suspicious for additional pathology in addition to PC. After an exhaustive evaluation, a neoplastic or infectious disease process was ruled out. Even though the patient presented with a clinical deterioration of respiratory function compatible with secondary acute respiratory distress syndrome, there was a complete recovery after supportive measures and supplemental oxygen. In conclusion, the nonspecific clinical and imaging findings in patients with pulmonary contusion warrant a complete evaluation of these cases. An early diagnosis is essential to establish adequate support and monitoring to prevent possible complications that could worsen the patient’s prognosis.

Background: Structural disorders of hemoglobin are a group of rare and fatal genetic diseases that disrupt the transport and exchange of oxygen in the blood, causing tissue damage and ultimately leading to chronic conditions. The hemoglobin (Hb) S variant predominantly impacts individuals of Afro-descendant heritage. A significant concentration of the Afro-descendant population in Colombia, notably 12.5 %, is found in the city of Cali. Previous research has identified this city's structural hemoglobin disorders prevalence rate of 3.78 %. The aim of this study was to determine the prevalence of HbC, HbS, HbF, and HbA2 variants within a population who underwent HbA1c testing, as well as the prevalence of chronic diseases among patients with these hemoglobin alterations, at a high-complexity hospital in the city of Cali from 2015 to 2019. Methods: A descriptive observational study was conducted, involving a study population that comprised patients with both suspected and monitored diagnoses of diabetes. The cohort was selected from a high-complexity hospital in Cali. A total of 15,608 patients were included in the analysis, all of whom underwent HbA1C measurement through capillary electrophoresis, which also offers an indirect diagnosis of certain structural disorders of hemoglobin. Bayesian methods were employed for frequency analysis. Results: Among the 15,608 patients assessed, 63.6 % (n = 9920) were women. The overall prevalence of structural hemoglobin disorders was 1.98 % (n = 287, 95 % CI = 1.77 %–2.21 %). The co-occurrence of diabetes and kidney disease emerged as the most prevalent combination of pathologies observed in individuals with HbC, for both men and women across various age groups: 18–42 (58.3 % and 50.0 % respectively), 43–55 (50.0 % for both), 56–65 (50.0 % and 37.5 % respectively), and >65 years (66.7 % and 57.1 % respectively). Conclusions: The observed prevalence of the studied variants exceeded 1 %, a threshold underscored by the World Health Organization (WHO) as epidemiologically significant. Among HbC and HbS-positive patients, the elevated prevalence of diabetes and kidney disease is a guiding factor in developing proactive prevention strategies.

Infection by Aspergillus covers a broad clinical spectrum, including invasive pulmonary aspergillosis (IPA) and its disseminated extrapulmonary form, invasive aspergillosis (IA). It typically occurs in severely immunocompromised hosts, but it sometimes affects the immunocompetent population, especially patients with acute diseases being treated at the intensive care unit (ICU) and less often those with chronic conditions. In this article, we report the case of a 50-year-old male, with diabetes mellitus (DM) as the only risk factor, treated for IPA and IA with cardiac and central nervous system (CNS) involvement at a high complexity institution in Cali-Colombia. Clinical presentation and radiological findings are unspecific and require a high level of suspicion. To confirm the case, histological or cytological of the fungus is required; histopathological examination of lung tissue is the gold standard, but it is difficult to perform due to respiratory compromise and high risk of bleeding, so bronchoscopy and bronchoalveolar lavage (BAL) plays an essential role in the diagnostic process. A diagnostic algorithm that includes risk assessment, symptoms, imaging findings, and isolation in cultures is essential to allow the diagnosis and initiation of treatment promptly, which includes a combination of surgery and antifungal medications for long periods, even life-long treatment.

Central airway obstruction refers to the occlusion of more than 50% of the trachea, main stem bronchi, or lobar bronchus. It can potentially become a life-threatening condition. Pulmonary hamartomas (PH) are rare tumors with an incidence of 0.25%, constituting about 8% of all benign lung neoplasms. Only 10% of PH occur endobronchially, while the remaining appear peripherally. We present the case of a women with an endobronchial hamartoma that required emergent resection by bronchoscopy. This is 44-year-old woman, with a history of an endobronchial mass on the right main stem bronchus (RMSB) without histopathological diagnosis or surgical management. She presented with a history of chronic cough and expectoration. Upon admission, a chest X-ray was performed, showing opacities of the right lung and amputations of the RMSB. Bronchoscopy was performed and a tumor-like mass that occludes the RMSB was found, with valve effect causing intermittent occlusion. In anesthetic induction, she presents severe airway obstruction and cardiorespiratory arrest. During resuscitation maneuvers, the lesion that was obstructing the light is seen and resection was performed with electrocautery and cryotherapy probes. Histopathological report described an endobronchial chondromesenchymal hamartoma, with no signs of malignancy. The control X-ray showed adequate re-expansion of the right lung. In conclusion, although endobronchial hamartoma has a low incidence and has a slow growth rate, it can manifest as severe airway obstruction. To achieve a complete resection of an endobronchial lesion, both rigid and/or flexible bronchoscopy plus multimodal interventions are recommended.

Sjögren's Syndrome (SS) is an autoimmune inflammatory disease, characterized by lymphocytic infiltration of exocrine glands. Approximately 10% of patients with SS have pulmonary involvement as the first manifestation of their disease, the most common being non-specific interstitial pneumonia.We present the case of a 51-year-old man with organizing pneumonia as the presenting feature of primary SS.Pulmonary involvement as the presenting feature of SS is uncommon, especially when the pattern on CT-scan is that of organized pneumonia. Initial management includes steroids and other immunosuppressants agents, with a better response in organized pneumonia secondary SS cases.

Abstract The advent of immune-checkpoint inhibitors (ICI) in modern oncology has significantly improved survival in several cancer settings. A subgroup of women with breast cancer (BC) has immunogenic infiltration of lymphocytes with expression of programmed death-ligand 1 (PD-L1). These patients may potentially benefit from ICI targeting the programmed death 1 (PD-1)/PD-L1 signaling axis. The use of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarkers has been under intense examination. Emerging data suggest that TILs are associated with response to both cytotoxic treatments and immunotherapy, particularly for patients with triple-negative BC. In this review from The International Immuno-Oncology Biomarker Working Group, we discuss (a) the biological understanding of TILs, (b) their analytical and clinical validity and efforts toward the clinical utility in BC, and (c) the current status of PD-L1 and TIL testing across different continents, including experiences from low-to-middle-income countries, incorporating also the view of a patient advocate. This information will help set the stage for future approaches to optimize the understanding and clinical utilization of TIL analysis in patients with BC.

Given the benefits and likely future applications, there is an urgent need to expand the use of next-generation sequencing (NGS) in breast, lung, and unknown primary cancers in Colombia. The objective of this review is to address the barriers limiting access to the use of NGS in Colombia, specifically for patients with breast, lung, and unknown primary cancers in the public health care system. A selected Panel of Colombian experts in NGS were provided with a series of relevant questions to address in a multiday conference. Each narrative was discussed and edited by the Panel through numerous drafts and rounds of discussion until consensus was achieved. There are limitations to the widespread adoption of innovative technology inherent to the Colombian health care system. Barriers identified to implementing NGS in Colombia include availability, accessibility, and affordability; limited infrastructure; training and awareness of health personnel; quality-control procedures; and collection of local data. Stakeholders must align to adapt the implementation of NGS to the constraints of resource-limited environments. Diagnostic algorithms were developed to guide molecular testing for lung, breast, and unknown primary cancers. Recommendations on overcoming the barriers to the widespread adoption of NGS include country-specific molecular testing guidelines, creating a national genetic registry, improving infrastructure, and creating health policy that favors the adoption of innovative technology.

BackgroundOur previous study reported higher mRNA levels of the human epidermal growth factor receptor 2 (HER2)-amplicon genes ERBB2 and GRB7 in estrogen receptor (ER)-positive breast cancer patients with relatively high Indigenous American (IA) ancestry from Colombia. Even though the protein expression of HER2 and GRB7 is highly correlated, they may also express independently, an event that could change the patients’ prognosis. In this study, we aimed to explore the differences in ER, HER2 and GRB7 protein expression according to genetic ancestry, to further assess the clinical implications of this association.MethodsWe estimated genetic ancestry from non-tumoral breast tissue DNA and assessed tumoral protein expression of ER, HER2, and GRB7 by immunohistochemistry in a cohort of Colombian patients from different health institutions. We used binomial and multinomial logistic regression models to test the association between genetic ancestry and protein expression. Kaplan-Meier and log-rank tests were used to evaluate the effect of HER2/GRB7 co-expression on patients’ survival.ResultsOur results show that patients with higher IA ancestry have higher odds of having HER2+/GRB7- breast tumors, compared to the HER2-/GRB7- subtype, and this association seems to be stronger among ER-positive tumors (ER+/HER2+/GRB7-: OR=3.04, 95% CI, 1.47-6.37, p

Abstract Background Primary malignant tumors of the aorta are extremely rare. They are frequently located in the abdominal aorta, followed by the thoracic aorta. Sarcomas are the most common histological type. These tumors originate from the middle or intimal layer, the latter being the most common. Symptoms and radiological findings are generally nonspecific. Since their growth is endovascular, embolic phenomena can occur leading to occlusive signs and symptoms. Case presentation We describe the case of a 75-year-old Hispanic man, a former tobacco smoker, with a history of pain and epigastric tenderness, dysphagia, and weight loss of approximately 6 kg. A thorax computed tomography scan showed a mass within the posterior mediastinum with poorly defined borders and heterogeneous density, located between thoracic vertebra 5–8, with a size of 78 × 53 × 76 mm, with left main bronchus compression. Endobronchial ultrasound-guided transbronchial needle aspiration was performed; it found an extrinsic posterior compression of the left main bronchus with no endobronchial injury. An intimal angiosarcoma of the thoracic aorta was diagnosed. Conclusion Tumors of the aorta are rare and difficult to diagnose; they are a challenge during the diagnosis, since they usually require open surgical procedures. Endobronchial ultrasound-guided transbronchial needle aspiration associated with rapid on-site examination offered, in this case, the possibility of a successful diagnosis, avoiding major procedures. This is the first case reported in the literature of an intimal angiosarcoma of the thoracic aorta diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration.

Abstract Background The sternum is considered an unusual tumor site, corresponding to 15% of all thoracic wall tumors. Primary sternal tumors are even rarer and most commonly malignant. We present the case of a young man who consulted with a painful sternal mass, which after its resection is confirmed to be a cavernous hemangioma. Case presentation A 39-year-old man, with unremarkable medical history besides a 2-year-long sternal pain, non-irradiated, which worsens over the last few months and is accompanied by the appearance of a sternal palpable mass. On physical exam, there was a bulging of the sternal manubrium, with no inflammatory changes. Thoracic CT scan shows an expansive and lytic lesion of the sternum, compromising the manubrium and extending to the third sternocostal joint, without intrathoracic compromise nor cleavage plane with mediastinal vascular structures. The patient is taken to resection of the mass and sternal reconstruction using prosthetic material and pectoral and fasciocutaneous muscular flaps. Histopathological findings: cavernous hemangioma with negative borders and no other malignant findings. Conclusions Sternal hemangiomas can cause defects in the bone structure and show an expansive growth, challenging the differentiation between a benign or malignant lesion. Therefore, they should be considered malignant until shown otherwise. Management involves radical surgery with curative purposes and posterior reconstruction to improve quality of life, as shown with our patient.

Abstract Tuberculosis is currently considered a public health issue worldwide. Although a large number of hematological disorders related to tuberculosis have been described, immune thrombocytopenic purpura in patients with active tuberculosis is very rare but must be considered in a patient with no other evident cause.

Abstract Background Myospherulosis develops as the result of a reaction between exogenous lipids and red blood cells (RBC) of the patient, being the latter injured when perceived as a foreign body by the immune system, triggering an intense inflammatory response. Case presentation A 63-year-old man with a history of dyslipidemia, Barret’s esophagus, and coronary disease, who was taken to thoracoscopy and left inferior lobectomy due to the presence of a pulmonary mass. A primary pulmonary adenocarcinoma was diagnosed. On follow up a PET-CT was performed, in which a metabolically active lesion was described adjacent to the prior lobectomy, suggesting a local relapse. EBUS-TBNA was then performed, obtaining a sample from which histopathological pattern compatible with myospherulosis was obtained. Conclusions Although it is a rare entity, myospherulosis has a well-defined morphological pattern. By not recognizing myospherulosis as a benign lesion, a patient’s risk of invasive cancer can be overestimated. It is a phenomenon found with increasing frequency and has been reported in different tissues, however, this is the first report in the literature of myospherulosis of the lung. Greater awareness is required regarding the existence of this phenomenon.

Abstract Background Primary effusion lymphoma is a rare, high-grade non-Hodgkin’s lymphoma that usually occurs in immunosuppressed or human immunodeficiency virus-positive individuals in advanced stages of the disease. However, primary effusion lymphoma occasionally affects immunocompetent patients who are infected with human herpes virus type 8 or Epstein-Barr virus. This disease manifests with liquid collections in cavities, producing constitutional symptoms; fever; weight loss; and symptoms related to extrinsic compression, such as dyspnea or abdominal discomfort. Diagnosis is confirmed with cytological or tissue evaluation showing large, multinucleated lymphoid cells with positive specific markers for the disease, such as CD45 and markers related to viral infections, when present. There is no standard treatment for primary effusion lymphoma, but several chemotherapy protocols are recommended, usually with poor results. Case presentation We present a case of an adult human immunodeficiency virus-negative Hispanic origin woman with primary effusion lymphoma with pleuritic, pericardial, and peritoneal compromise who also had unusual complications during a diagnostic procedure: the accidental rupture of the left ventricle and the development of a secondary left ventricular pseudoaneurysm. We describe the clinical, radiological, and laboratory characteristics as well as the outcome of this case. Conclusions Primary effusion lymphoma is a very rare entity that represents 4% of non-Hodgkin’s lymphoma cases associated with human immunodeficiency virus and 0.1% to 1% of all lymphomas in patients with another type of immunodeficiency in regions where human herpes virus type 8 is not endemic. This reported case is an unusual presentation of primary effusion lymphoma because it occurred in an immunocompetent human immunodeficiency virus-negative adult woman without the presence of Kaposi’s sarcoma or Castleman’s disease and for whom the clinical course after chemotherapy was successful. However, the rupture of the free wall of the left ventricle is a very rare catastrophic event that usually occurs after myocardial infarction. Left ventricle free wall rupture rarely goes unnoticed, but when it occurs, it leads to the development of a ventricular pseudoaneurysm in which the rupture is contained by the pericardium with an organized thrombus and an adjacent hematoma.

Abstract Background Endothelial growth factor receptor (EGFR) mutations are an essential driver of personalized therapy for patients with lung cancer and are detected in approximately 15% of Caucasian and 50% of Asian patients. EGFR tyrosine kinase inhibitors have been developed and used for this set of patients. T790M mutation in exon 20 is usually associated with secondary resistance to EGFR tyrosine kinase inhibitors therapy but is also present in treatment-naïve patients. The frequency for baseline T790M mutation varies from 4 to 35% according to the detection method used. Newer techniques have yielded higher rates, but concerns about false-positive results have been raised. Compound mutations account for 4–14% of all EGFR-mutated tumors, with no studies yet to provide a frequency rate for T790M + 19 deletion association due to the small number of cases. However, there are reports that pretreatment T790M + L858R association is significantly more frequent compared to T790M + exon 19 deletion mutations. Diagnostic challenges, current knowledge on the subject, and therapeutic decisions are discussed. Case presentation We present the case of a 43-year-old Hispanic woman, a treatment-naïve patient, with metastasized lung cancer adenocarcinoma harboring a T790M deletion along with the classic 19 mutation. The initial symptoms were monoparesis of her left leg, associated with hyperreflexia, and hypoesthesia. In the absence of third-generation tyrosine kinase inhibitors, a platinum-based therapy was initiated with no response and she died 4 months after diagnosis. Conclusions Osimertinib seems to be a suitable therapy for treatment-naïve patients with sensitizing and resistant compound EGFR mutations. More studies regarding the clinical characteristics of these patients and the appropriate management of this condition are needed to provide the highest standard of care.

Adenoid cystic carcinoma is a rare tumor of low frequency, low grade malignancy and slow growth originating from the major and minor salivary glands. Its primary pulmonary presentation is very rare, it can manifest with central airway obstruction and extensive lung involvement. Although it is slow growing, it has a tendency to local recurrence and late hematogenous metastases. The cornerstone of management consists in the complete resection of the tumor. Radiotherapy and adjuvant chemotherapy have been used in a limited number of patients with unsatisfactory results. Therefore, clinical judgment is of vital importance for early diagnosis and adequate selection of patients for surgical management. We present two cases of patients with primary pulmonary adenoid cystic tumor with invasion of the carina treated with sleeve pneumonectomy and carinal resection with adequate response to the intervention. Keywords: Adenoid cystic carcinoma, Lung, Sleeve pneumonectomy, Carinal resection

Background: The term goiter is used to describe any abnormal growth of the thyroid gland, which can be diffuse or nodular, and can be associated with normal, diminished, or increased thyroid function. Multinodular goiter is a common disease whose prevalence increases at age 50. Clinical manifestations can be due to thyroid function impairment or related to size and location of the gland with compressive symptoms. Intrathoracic location is less frequent, can be mistaken with pulmonary lesions and usually implies a difficult surgical approach. Case presentation: A 66-year-old woman with a history of subtotal thyroidectomy presented with 7-month dyspnea, dry cough. There was no evidence of neck masses, or jugular engorgement. Physical examination was normal. Chest x-ray showed an 11 cm mass in the upper right hemithorax. Computed tomography (CT)-scan, showed calcifications, and compression of the superior vena cava without infiltration, the right subclavian vein and left displacement of the trachea. Distinction between intrapulmonary or mediastinal location was not clear. Biopsy showed thyroid origin, and bilateral thoracotomy was performed with confirmation of a giant multinodular goiter. Conclusions: Intrathoracic goiter should undergo surgical or ablative management if compressive symptoms of the airway and cervical or thoracic vessels are present. The large size of the tumor along with the presentation after thyroidectomy and the seeming location in the right upper lobe made this particular case striking. Specially in the elderly, multidisciplinary perioperative management is key for a successful recovery.

Background: Squamous cell lung carcinoma(SCLC), accounts for 20% of lung cancer(LC). The binding of programmed cell death 1(PD-1) to its ligand PD-L1 is a key checkpoint regulator of immune response, and overexpression of the latter leads to immune surveillance escape. This might represent an important oncogenic mechanism, as well as a predictor for immunotherapy treatment success in SCLC. Methods: A retrospective series of 24 patients with SCLC was included(2009–2013). These patients presented with a single pulmonary lesion and no history of previous cancer. Expression of PD-L1 was evaluated on tumoral biopsies with immunohistochemistry. PD-L1 tumor proportion score(TPS) was considered high when ≥50%. Clinical characteristics regarding diagnosis were reviewed and recorded. Data were analysed in STATA v.14®. Results: Twenty four patients were included in this series. Mean age was 67 + 14 years, and 62.5% were men. Smoking status was positive in 54%. Cancer stage IV was present in 54%. PD-L1 was positive in 13(54%). (+)PD-L1 was more frequent in smokers than in non-smokers(11 vs 2)(p = 0.001), as well as in COPD patients(p = 0.006). General overall survival was 21.8% at 5 years. Overall survival at one year in PD-L1(+) was 30.7% and 72.7% for PD-L1(-) patients. Survival median for PD-L1(+) patients was 10.5mo, as well as for the whole series. Conclusion: Patients with primary SCLC who have a high PD-L1 TPS, had a worse overall survival than their counterparts. PD-L1 expression in SCLC in a Colombian sample lies between the one found in the literature.

Spondyloarthropathies are a group of chronic inflammatory disorders that involve the joints of the axial skeleton, peripheral joints and have extra-articular manifestations. Treatment includes inhibitors of tumor necrosis factor α. Currently there are five approved inhibitors: a soluble receptor, Etanercept and four monoclonal.Etanercept has very low toxicity with pulmonary adverse reactions being very rare. We present the case of a patient who developed respiratory symptoms and pulmonary infiltrates of rapid evolution after the third dose of treatment with Etanercept.

Anaplastic large cell lymphoma (ALCL) is a rare type of non-Hodgkin lymphoma (NHL) originated from mature post thymic T cells. They represent 1–3% of NHL. Different subtypes have been described: Anaplastic lymphoma kinase (ALK)-negative ALCL, ALK-positive ALCL and breast implant-associated ALCL. ALK-positive ALCL affects mainly the young and has better prognosis. We present a case report of an adult woman with AKL-positive ALCL, diagnosed by endobronchial ultrasound-guided transbronchial needle aspirate (EBUS-TBNA).A 59-year-old women with no history of breast implants, was admitted for a four-month low back pain. Initially, the patient was treated for a spondyloarthropathy, but due to persistence of the symptoms, a lumbosacral MRI was performed, showing changes in morphology and signal intensity in the vertebral body of L3, along with edema and a paravertebral collection that affected the left psoas muscle, suggesting granulomatous spondylodiscitis. Chest CT-scan showed mild left pleural effusion, subcarinal and right hiliar adenomegalies. An EBUS-TBNA with ROSE (rapid on-site evaluation) was performed showing positive findings for malignancy, suggestive of hematolymphoid neoplasia. Pathology analysis showed an AKL-positive ALCL. Additionally, a biopsy of paravertebral tissue biopsy was obtained, which was consistent with the nodal sample. Chemotherapy was initiated with the CHOP protocol: cyclophosphamide, hydroxydaunorubicin, vincristine sulfate and prednisone.EBUS-TBNA is a minimally invasive and safe technique for obtaining mediastinal samples. Collaboration with a cytopathologist trained to perform ROSE improves the diagnostic performance. Keywords: Anaplastic large cell lymphoma (ALCL), Anaplastic lymphoma kinase (ALK), NonHodgkin lymphoma, EBUS-TBNA, Rapid on-side evaluation (ROSE)

Plastic bronchitis is a rare and underdiagnosed disease characterized by the formation and expectoration of bronchial casts of amorphous material, which can be potentially fatal. It is more frequent in pediatric population. Symptoms can range from chronic cough and dyspnea to respiratory failure depending on the area of the compromised airway. Casts are classified as type I when constituted by inflammatory cells and accompany diseases such as asthma and pneumonias; and type II when acellular and are associated with congenital heart diseases following procedures such as Fontan.We report the case of a male schoolchild with a history of complex congenital heart disease, treated with palliative surgery, evaluated in the emergency department for cough and respiratory distress. The mother referred expulsion of gelatinous material after coughing. During clinical evaluation, expulsion of bronchial casts was evidenced, suggesting a plastic bronchitis. He underwent a diagnostic and therapeutic bronchoscopy and received initial treatment with respiratory therapy, nebulized hypertonic saline solution, mucolytics, dornase alpha and nebulized heparin. The hospitalization revealed a stenosis of the right pulmonary artery, which was corrected with stent. The patient progressed satisfactorily with improvement of cough and expectoration. He was discharged with combined treatment, nebulized medications and those concerning his underlying disease. Keywords: Plastic bronchitis, Bronchial casts, Congenital heart disease, Fontan

Background Cyclin D1-positive B cells are occasionally found in the mantle zones of reactive lymphoid follicles, a condition that has been called “in situ mantle cell lymphoma”. The clinical significance of this lesion remains uncertain.Design and Methods The clinical and pathological characteristics, including SOX11 expression, of 23 cases initially diagnosed as in situ mantle cell lymphoma were studied.Results Seventeen of the 23 cases fulfilled the criteria for in situ mantle cell lymphoma. In most cases, the lesions were incidental findings in reactive lymph nodes. The t(11;14) was detected in all eight cases examined. SOX11 was positive in seven of 16 cases (44%). Five cases were associated with other small B-cell lymphomas. In two cases, both SOX11-positive, the in situ mantle cell lymphoma lesions were discovered after the diagnosis of overt lymphoma; one 4 years earlier, and one 3 years later. Twelve of the remaining 15 patients had a follow-up of at least 1 year (median 2 years; range, 1–19.5), of whom 11 showed no evidence of progression, including seven who were not treated. Only one of 12 patients with an in situ mantle cell lymphoma lesion and no diagnosis of mantle cell lymphoma at the time developed an overt lymphoma, 4 years later; this case was also SOX11-positive. The six remaining cases were diagnosed as mantle cell lymphoma with a mantle zone pattern. Five were SOX11-positive and four of them were associated with lymphoma without a mantle zone pattern.Conclusions In situ mantle cell lymphoma lesions are usually an incidental finding with a very indolent behavior. These cases must be distinguished from mantle cell lymphoma with a mantle zone pattern and overt mantle cell lymphoma because they may not require therapeutic intervention.