Dermatomyositis with Eosinophils

Dermatomyositis is an idiopathic inflammatory myopathy that often presents with symmetric proximal skeletal muscle weakness and characteristic skin findings. Typical skin biopsy findings include vacuolar changes of the basal layer, increased dermal mucin, and a predominantly lymphocytic infiltrate. We report a case of dermatomyositis presenting as intensely pruritic papules and plaques, with initial histopathology being atypical of dermatomyositis due to the presence of eosinophils. The initial biopsy demonstrated a superficial dermatitis with eosinophils, initially thought to represent a drug eruption. A second biopsy of the same cutaneous manifestation was performed at a later time given high clinical suspicion for dermatomyositis and demonstrated a more classic vacuolar interface dermatitis with increased mucin and an absence of eosinophils. Notably, increased pruritus was specifically associated with the lesion that demonstrated tissue eosinophilia. The case illustrates the importance of considering tissue eosinophilia in the histologic presentation of dermatomyositis.

Primary Gastric Signet Ring Cell Carcinoma or Metastatic Lobular Carcinoma With Signet Ring Cells: A Diagnostic Challenge

Histologically, cells having vacuolated cytoplasm rich in mucin and pushing the nucleus to the periphery are indicative of signet ring cell carcinoma. This condition often affects the digestive system. On the other hand, it is a very uncommon subtype of invasive lobular breast carcinoma, with a higher probability (more than invasive breast carcinoma of no special type {IBC-NST}) to migrate to the stomach, spleen, urinary tract, and uterus. As with other metastatic carcinomas of breast origin, metastatic signet ring cell carcinoma of the breast is often treated with systemic therapies such as chemotherapy or hormonal therapy. However, surgical resection and eventual perioperative chemotherapy are usually recommended in case of primary gastric ring cell carcinomas that are non-metastatic. As a result, misdiagnosis might result in unneeded gastrectomy and chemotherapy, which would result in considerable mortality and morbidity. We report a case of mammary lobular carcinoma with signet ring cells metastatic to the stomach, a variant rarely described and challenging to distinguish from primary gastric signet ring carcinoma.

Sclerosing Fibroadenoma With Atypical Ductal Hyperplasia Mimicking Invasive Carcinoma: A Case Report With Diagnostic Pitfall

Fibroadenoma (FA) of the breast is a benign fibroepithelial lesion rarely showing atypical epithelial overgrowth. We present the case of a 50-year-old Japanese woman with sclerotic FA with atypical ductal hyperplasia (ADH)/ductal carcinoma in situ (DCIS). A small mass was detected during clinical examination in the upper lateral area of the left breast. Hematoxylin and eosin stain section of a breast needle core biopsy specimen showed trabecular growth of atypical epithelial cells without distinct myoepithelial lining in the sclerotic stroma. Initial pathological diagnosis of the biopsy specimen was invasive carcinoma of no special type. The surgical specimens included a well-bordered nodular lesion with similar histological findings to that of the biopsy specimen, but, the myoepithelial lining was highlighted by cytokeratin 5 (CK5) immunohistochemistry. The tumor cells were diffusely ER-positive and completely negative for CK5 in immunohistochemical staining. Final diagnosis based on the results of immunohistochemical staining and consultation between two breast pathology specialists was the lesion as sclerosing FA with ADH/DCIS. Awareness of the unique histological subtype of FA is important to avoid pathological misdiagnosis and clinical overtreatment.

A Case Report and Literature Review of Rectosigmoid Crohn's Disease: A Diagnostic Pitfall Ultimately Leading to Spontaneous Colonic Perforation

Inflammatory bowel disease (IBD) is a chronic condition that affects the gastrointestinal tract, with ulcerative colitis (UC) and Crohn's disease (CD) as the two major entities. While these conditions share some similarities in clinical presentation, they have distinct histopathological features. UC is a mucosal disease affecting the left colon and rectum, while CD can affect any part of the gastrointestinal tract and all layers of the bowel wall. Accurate diagnosis of UC and CD is important for effective management and prevention of complications. However, distinguishing between the two conditions based on limited biopsy specimens or atypical clinical presentations can be challenging. We present a case of a patient diagnosed with UC based on a single endoscopic biopsy from the sigmoid colon, who later presented with colonic perforation and was found to have CD on the colectomy specimen. This case emphasizes the importance of clinical guidelines when dealing with any patient of suspected IBD, considering alternative diagnoses in patients with atypical presentations and the need for careful clinical, endoscopic, and histological evaluation to make an accurate diagnosis. Delayed or missed diagnosis of CD can lead to significant morbidity and mortality.

Clinicopathological and molecular features of indolent natural killer-cell lymphoproliferative disorder of the gastrointestinal tract

AIMS

Indolent natural killer (NK) cell lymphoproliferative disorder of the gastrointestinal (GI) tract (iNKLPD) is a rare, recently recognised neoplasm. Most of the reported tumours are confined to the GI tract, while a small subset of the tumours harbour JAK3 mutations. We collected four cases of iNKLPD with the goal of adding additional information to the current knowledge of this disease regarding the clinicopathological, immunohistochemical and molecular features.

METHODS AND RESULTS

Similar features including medium- to large-sized lymphoid cells with variable amounts of pale or slightly eosinophilic cytoplasm, and no evidence of EBER, TCR rearrangement were found in four cases. JAK3 K563_C565del mutation was found in one of three cases that were subjected to targeted next-generation sequencing. Unique findings of our study include one iNKLPD encountered for the first time in nasopharynx, where lesions could be inadvertently diagnosed as extranodal NK/T cell lymphoma, and one iNKLPD located in the gallbladder extended deeply into muscular and adventitial layers. Exceptional CD8-positive expression was observed in one iNKLPD. In addition, positive staining of phospho-STAT5, phospho-STAT3 and phospho-p38 were found in our cases. None of the four patients received therapy for lymphoma, but all had a benign clinical outcome during a follow-up time of 20-99 months.

CONCLUSIONS

We present four iNKLPDs with clinical, immunohistochemical and molecular features similar to the reported cases, as well as some unusual characters, which expand our knowledge on this disease, and further support the neoplastic nature of iNKLPDs.

The Fallacy of a Single Diagnosis

BACKGROUND

Diagnostic reasoning requires clinicians to think through complex uncertainties. We tested the possibility of a bias toward an available single diagnosis in uncertain cases.

DESIGN

We developed 5 different surveys providing a succinct description of a hypothetical individual patient scenaric. Each scenario was formulated in 2 versions randomized to participants, with the versions differing only in whether an alternative diagnosis was present or absent. The 5 scenarios were designed as separate tests of robustness using diverse cases, including a cautious scenario, a risky scenario, a sophisticated scenario, a validation scenario, and a comparative scenario (each survey containing only 1 version of 1 scenario). Participants included community members (n = 1104) and health care professionals (n = 200) who judged the chances of COVID infection in an individual patient.

RESULTS

The first scenario described a cautious patient and found a 47% reduction in the estimated odds of COVID when a flu diagnosis was present compared with absent (odds ratio = 0.53, 95% confidence interval 0.30 to 0.94, P = 0.003). The second scenario described a less cautious patient and found a 70% reduction in the estimated odds of COVID in the presence of a flu diagnosis (odds ratio = 0.30, 95% confidence interval 0.13 to 0.70, P < 0.001). The third was a more sophisticated scenario presented to medical professionals and found a 73% reduction in the estimated odds of COVID in the presence of a mononucleosis diagnosis (odds ratio = 0.27, 95% confidence interval 0.10 to 0.75, P < 0.001). Two further scenarios-avoiding mention of population norms-replicated the results.

LIMITATIONS

Brief hypothetical scenarios may overestimate the extent of bias in more complicated medical situations.

CONCLUSIONS

These results demonstrate that an available simple diagnosis can lead individuals toward premature closure and a failure to fully consider additional severe diseases.

HIGHLIGHTS

Occum's razor has been debated for centuries yet rarely subjected to experimental testing for evidence-based medicine.This article offers direct evidence that people favor an available simple diagnosis, thereby neglecting to consider additional serious diseases.The bias can lead individuals to mistakenly lower their judged likelihood of COVID or another disease when an alternate diagnosis is present.This misconception over the laws of probability appears in judgments by community members and by health care workers.The pitfall in reasoning extends to high-risk cases and is not easily attributed to information, incentives, or random chance.

Revisiting the cytologic features of autoimmune pancreatitis: An institutional experience

BACKGROUND

Autoimmune pancreatitis (AIP) is a known mimicker of pancreatic ductal adenocarcinoma both clinically and radiologically. In this study, the authors present their institutional experience in diagnosing AIP on cytology and correlate results with the histologic findings.

METHODS

A 14-year computerized search for patients who had histologically confirmed AIP with concurrent or prior cytology was performed. Clinical data, cytology findings, and surgical pathology results were reviewed for analysis.

RESULTS

Eighteen patients were identified. The patients showed a male predominance, with a mean age of 59 years. Jaundice, weight loss, and abdominal pain were the most common clinical presentation. Five of 12 patients who were tested for serum immunoglobulin G4 had elevated levels. Cytologic findings of 16 cases that were available for review showed markedly inflamed fibrous stroma (54%) and cytologic atypia (50%). The final cytologic diagnoses were suspicious for adenocarcinoma (n = 1), atypical (n = 8), and benign/negative (n = 9). The corresponding surgical pathology diagnoses were classified as type 1 (n = 10), type 2 (n = 6), and AIP, not otherwise specified (n = 2). All type 2 AIP cases had at least atypical cytologic diagnoses, with one called suspicious for adenocarcinoma and another called adenocarcinoma at the time of rapid on-site evaluation. In contrast, eight of 10 type 1 AIP cases were negative/benign, and two of 10 were atypical. In these two atypical cases, the possibility of AIP was raised because of the presence of inflamed stroma.

CONCLUSION

AIP is a pitfall in cytology because moderate-to-marked atypia can be present, especially in type 2 AIP. Because atypia can be severe, the presence of cellular fibrous stroma with lymphocytic stromal infiltrates and the integration of serum immunoglobulin G4 levels could be helpful in avoiding diagnostic overcall in AIP.

Interference of Known or Suspected Endometriosis in Reporting FDG PET/CT Performed in Another Indication

INTRODUCTION

Endometriosis is a common gynecologic condition that may be visualized on 18F-FDG PET/CT and mimic lesions of malignancy. We analyzed the interference of known or suspected endometriosis in reporting 18F-FDG PET/CT performed in another indication.

RESULTS

The PET/CT images of 18 women with known (n = 15) or suspected (n = 3) endometriosis were analyzed. Based on clinical follow-up and results of other imaging, biopsy, and/or postsurgical histology, the presence of lesions of endometriosis at the time of 18F-FDG PET/CT was confirmed in 13 of 18 patients (72%). The per-patient positivity rate of 18F-FDG PET/CT was 8/18 (44%; 95% confidence interval, 22%-69%). The patient-based detection rate of 18F-FDG PET/CT in patients with confirmed lesions of endometriosis was 8/13 (62%; confidence interval, 32%-86%). On per-lesion/site basis, 18F-FDG PET/CT detected 11 of 20 sites (55%) of endometriosis. The SUVmax of these lesions/sites ranged between 1.8 and 5.3 (median, 3.8). In 9 of 18 patients (50%), a total of 13 non-endometriosis-related lesions/sites were detected by 18F-FDG PET/CT; their SUVmax ranged between 2.7 and 23 (median, 9.4).

CONCLUSION

The interference of known or suspected endometriosis in reporting 18F-FDG PET/CT performed in another indication was limited but possible and should be kept in mind, even in postmenopausal women, as the oldest patient with 18F-FDG-positive endometriosis was aged 63 years. The lesions of endometriosis showed inconstant 18F-FDG uptake with overlap of SUVmax with low-grade malignancies. In our series, the greatest SUVmax value of lesion of endometriosis was 5.3, somewhat higher than the threshold of 4 previously proposed for identification of malignant transformation of endometriosis.

Hyaline Vascular Type of Castleman Disease: Diagnostic Pitfalls on Cytology and Its Clinical Relevance

Castleman disease (CD) is an uncommon cause of lymphadenopathy. The role of fine-needle aspiration cytology (FNAC) as a diagnostic modality in this disease is not well established. Cytological features of CD have a considerable overlap with many reactive conditions. It has subtle morphological features; which if overlooked, may miss the diagnosis. A two-year-old girl presented with cervical lymphadenopathy. FNAC of the cervical lymph node showed features of granulomatous lymphadenitis. Excision biopsy revealed the hyaline vascular type of CD. Cytological smears were reviewed carefully and revealed indicators of CD. These included capillary fragments with adherent reactive lymphoid cells, plump endothelial cells and pale pink material admixed with germinal center cells. The collections of plump endothelial cells had been misinterpreted as granulomas previously. This report highlights the subtle cytomorphological pointers of CD. Careful scrutiny for these features could aid the cytologist in differentiating CD from other reactive and neoplastic disorders, thus avoiding cytodiagnostic pitfalls. This case study reiterates an important fact that for a lymph node lesion, histopathology plays a crucial role in differentiating mimickers and renders an accurate diagnosis.

Follicular T-cell lymphoma mimicking lymphocyte-rich classic Hodgkin lymphoma: a case report of a diagnostic pitfall

Follicular T-cell lymphoma (FTCL), one of the nodal T-cell lymphomas with T follicular helper (T_^FH) phenotype, is an uncommon disease. The diagnosis of FTCL is challenging on the distinction from the morphological mimics mostly exemplified by follicular lymphoma. Here, we described a case of FTCL that mimicked lymphocyte-rich classic Hodgkin lymphoma (LRCHL). A 47-year-old male presented with cervical lymphadenopathy. The biopsy specimen demonstrated nodular lymphoid proliferation, which included scattered CD30+ CD15- CD20- PAX5 weakly+ Hodgkin and Reed-Sternberg (HRS)-like cells and a rich distribution of CD3+ CD4+ PD1+ T-cells. Epstein Barr virus was not detected in HRS-like cells, but it was detected in a small proportion of the scattered lymphocytes. The large cells were also negative for programmed cell death ligand 1, which appeared to be coincidental as described in our previous report of LRCHL. However, flow cytometry showed a CD3- CD4+ T-cell population that constituted 37.4% of all gated lymphocytes. A PCR analysis showed a clonal T-cell receptor-gamma gene rearrangement, but not a clonal immunoglobulin heavy chain gene rearrangement, and showed RHOA G17V mutation. The constellation of these findings led us to revise the diagnosis to FTCL. This result indicated that our case belonged to a relatively indolent subgroup of nodal peripheral T-cell lymphoma of T_^FH phenotype, which affects patients ≤60 years old, recently proposed by our group. This case report expands our understanding of the morphologic spectrum of FTCL and its clinicopathologic significance.

Expression of germinal center cell markers by extranodal marginal zone lymphomas of MALT type within colonized follicles, a diagnostic pitfall with follicular lymphoma

We reviewed 341 consecutive cases of marginal zone lymphoma (MZL) (47) or follicular lymphoma (FL) (294) of which 7 were difficult to distinguish due to perceived coexpression of BCL6 and BCL2 by tumor cells in follicular foci. This stimulated us to develop dual BCL6/BCL2 immunohistochemistry, allowing us to assess coexpression among individual cells. Dual staining confirmed coexpression in 6 of 7 cases, all extranodal MZL (ENMZL) based on overall features and representing 13% of MZL in this series. These findings confirm that MZL cells have plasticity regarding protein expression within the germinal center (GC) microenvironment, an important diagnostic pitfall. Intriguingly, in all MZL expressing BCL6, non-neoplastic GC B cells within colonized follicles showed diminished or absent CD10 expression but preserved BCL6 and high ki67. This finding suggests plasticity of CD10 expression in non-neoplastic GC B cells in the context of colonization by MZL, possibly related to NF-kB dysregulation.

Aberrant TTF-1 Expression in Peripheral T-Cell Lymphomas: A Diagnostic Pitfall

BACKGROUND

Thyroid transcription factor-1 (TTF-1) is a useful marker for identifying thyroid and lung cancers in diagnostic pathology, particularly for the investigation of unknown primary cancers. However, some other tumors such as colorectal cancer might aberrantly express TTF-1, particularly with the less specific clone SPT24. Occasional diffuse large B-cell lymphoma (DLBCL) cases have been reported to be TTF-1-positive, yet there is no information on TTF-1 expression in peripheral T-cell lymphoma (PTCL).

METHODS

We investigated a series of PTCL and DLBCL by immunohistochemistry for TTF-1 expression using 2 commercially available clones.

RESULTS

We found that 33% (5/15) adult T-cell leukemia/lymphomas (ATLLs) and 25% (2/8) angioimmunoblastic T-cell lymphomas (AITLs) were positive by clone SPT24 and only 2ATLL cases were positive by clone 8G7G3/1. Overall TTF-1 expression rates of PTCL by SPT24 and 8G7G3/1 were 16% (7/43) and 5% (2/43), respectively. All DLBCLs were negative.

CONCLUSION

Although TTF-1 is a relatively specific marker for thyroid and lung cancers, it might be expressed in some lymphomas, particularly PTCL when using clone SPT24. Pathologist should be aware of this possible diagnostic pitfall when using TTF-1 in investigating tumors of unknown origin.

Amelanotic Malignant Melanoma of the Male Urethra: A Potential Diagnostic Pitfall

A rare disease in an unusual site can closely mimic a typical presentation of a common disease, sometimes with devastating consequences. We present a case of primary amelanotic malignant melanoma of the urethra in a male, with clinical and histological characteristics that could have led to a mistaken diagnosis of high-grade urothelial carcinoma. Amelanotic mucosal melanoma should be suspected in all cases of high-grade mucosal tumors with practically any appearance (epithelioid, sarcomatoid, anaplastic, mixed). Morphological hints pointing toward melanoma-such as the presence of sparse melanin pigment or melanoma in situ-should be sought, and if absent, an immunohistochemical panel comprising S100 and HMB45 should be performed.

"Puffy shirt appearance": Cell crowding at low magnification may represent nevoid melanoma

BACKGROUND

Melanoma, particularly nevoid melanoma, can masquerade as benign. Helpful differentiating features include nuclear pleomorphism, atypia, prominent nucleoli, absent maturation, and increased mitotic figures. These can be subtle and easily missed unless carefully sought. Thus, the "puffy shirt appearance" concept was born from a Seinfeld episode in which the namesake character unintentionally agreed to wear a pirate-like puffy shirt. Consequently, he found himself out of place, sporting an outfit with "too much shirt in too little space". Similarly, at low-power, nevoid melanoma appears to have "too many cells in too little space". This is more pronounced and easier to appreciate when there is an associated nevus, where crowded, subtly malignant melanocytes stand out from the evenly distributed, more spaced out benign melanocytes.

METHODS

Twelve practicing dermatopathologists familiar with the puffy shirt concept in the context of melanoma were surveyed.

RESULTS

Hundred percent of participants found it most helpful as a triaging tool, prompting additional work up including higher magnification evaluation, additional levels, consultation, and/or immunohistochemistry.

CONCLUSIONS

The crowded cells in the "puffy shirt appearance" catch the eye and should provoke a more thorough inspection of the lesion. This sign is not pathognomonic for melanoma, but prompts more careful evaluation and helps prevent misdiagnosis.

Unilateral live twin tubal ectopic pregnancy presenting at 12 weeks of gestation: A case report

RATIONALE

Abdominal pain in pregnancy represents a demanding diagnostic challenge in the emergency department (ED) due to the extensive list of differential diagnoses to be considered, coupled with the possibility of each disease having nonclassical, atypical signs and symptoms, resultant from the patient's pregnant state. Additionally, emergency physicians (EPs) face limitations on investigative imaging modalities because of the need to minimize fetal radiation exposure. EPs have to tackle this diagnostic challenge while performing a balancing act to maximize both maternal and fetal outcomes in a time-sensitive manner, becauser any delays in decision-making at the ED may threaten the safety of mother and child. Two common causes of abdominal pain in pregnancy presenting to the ED are acute appendicitis and ectopic pregnancy. The latter is almost always diagnosed by 10 weeks of gestation. Here, we report an extremely rare case of unilateral live spontaneous twin tubal ectopic pregnancy presenting past 12 weeks of gestation, diagnosed after magnetic resonance imaging (MRI) of the abdomen.

PATIENT CONCERNS

A 37-year-old gravida 2 para 1 at 12 weeks and 6 days of gestation presented to our ED with a 2-day history of right iliac fossa pain, not associated with vaginal bleeding, fever, diarrhea, and vomiting. On examination, she was tachycardic (pulse rate 124 beats/min) and hypertensive (blood pressure 142/88 mm Hg). There was marked tenderness and guarding at the lower abdomen.

DIAGNOSES

Blood investigations were unremarkable, while abdominal ultrasonography found a live twin gestation with foetal heartbeats of 185 and 180 beats/min. MRI of the abdomen revealed an empty uterine cavity; 2 amniotic sacs and fetuses of diameter 10 cm, and a single placenta were noted in the right uterine adnexa. The patient was diagnosed with right live monochorionic diamniotic twin tubal pregnancy.

INTERVENTION

Our patient underwent emergency laparoscopic right salpingectomy.

OUTCOMES

The operation was successful and her postoperative care remained uneventful up to discharge.

LESSONS

Ectopic pregnancy cannot be ruled out based on prior normal antenatal examinations and gestational age of >10 weeks. EPs should not hesitate to order MRI scans for further evaluation if ultrasonography and laboratory findings are equivocal.

The 'White-eyed' Orbital Blowout Fracture: An Easily Overlooked Injury in Maxillofacial Trauma

The ‘white-eyed’ blowout fracture (WEBOF) is an injury that is often overlooked in head trauma patients, as it often has few overt clinical and radiographic features. Although benign in appearance, it can lead to significant patient morbidity. Here, we intend to increase the awareness of WEBOF and provide general principles for its diagnosis. WEBOF should be recognized early to ensure timely management and a successful outcome.

Diffuse Large B-Cell Lymphoma With Striking Intrasinusoidal Pseudoglandular Growth Pattern as a Diagnostic Dilemma Mimicking Metastatic Poorly Differentiated Pancreatic Adenocarcinoma in an Intraabdominal Lymph Node

We report an unusual intrasinusoidal growth pattern of an intraabdominal diffuse large B-cell lymphoma both clinically and histologically mimicking a metastatic adenocarcinoma. A 66-year-old woman presented with a high-grade distal biliary stricture with multiple enlarged abdominal lymph nodes. Frozen section at the time of pancreatoduodenectomy ("Whipple") demonstrated cohesive nests of large atypical cells within a totally effaced lymph node presenting a diagnostic challenge. Immunohistochemistry proved this to be a diffuse large B-cell lymphoma extensively involving the sinusoids.

Case of chondroid syringoma mimicking a nodular hidradenoma: A diagnostic pitfall on cytopathology

Limited literature is available on the use of fine needle aspiration (FNA) for skin tumors. Awareness of cytological features of these lesions is important to prevent misdiagnosis. A 45-year-old male, presented with slowly growing swelling over the thigh since 4 years. FNA from multiple sites yielded highly cellular smears with a dual cell population consisting of cells with small round nucleus scanty cytoplasm and polygonal cells with moderate to abundant cytoplasm. Extracellular basement membrane like material was also noted. A diagnosis of benign adnexal neoplasm, suggestive of nodular hidradenoma was made. Paraffin sections showed an encapsulated dermal tumor composed of ductal and myoepithelial cells in ducts, sheets, strands with chondromyxoid stroma. A final diagnosis of chondroid syringoma was given following evaluation of histopathology slides and Immunohistochemistry. FNA interpretation of skin tumors can be challenging since literature is limited. The placement of tumors into benign or malignant category is realistic and can direct management guidelines. Greater awareness of these lesions and following stringent diagnostic criteria can help in establishing a more accurate diagnosis.

A giant gastrointestinal stromal tumor of the stomach presenting as a posterior mediastinal mass

Gastrointestinal stromal tumors (GISTs) involving thoracic region are very rare, most of which are esophageal in origin. Herein, we report a gastric GIST presenting as a posterior mediastinal mass, which provided diagnostic pitfalls due to its unusual anatomic location. The patient was a 68-year-old Chinese female, presenting with dysphagia, nausea and weight loss of 5 kg within 4 months. The contrast-enhanced thoracic computed tomography scan revealed a huge heterogeneous soft tissue mass in the posterior mediastinum. The core biopsy revealed a spindle cell tumor. The pathological features, in conjunction with the strong immunostaining pattern for CD117 and DOG-1 and the identification of KIT exon 11 mutation, confirmed the diagnosis of GIST. The subsequent surgery revealed the tumor located entirely in the abdominal cavity, laying beneath the diaphragm, and pushing the diaphragm upward into the posterior mediastinum. To our best, there has been only one similar case reported in the English literature. As patients with GISTs either resectable or not may get potential benefits from imatinib currently, the identification of GIST is very important even before surgery. Clinicians and pathologists should keep in mind that GISTs involving thoracic region do exist. The morphological features, immunohistochemical panel including CD117 and DOG-1 and molecular genetic test, in combination with clinicopathological correlation are helpful in confirming the correct diagnosis.

Intrathyroidal parathyroid adenoma: Diagnostic pitfalls on fine-needle aspiration: Two case reports and literature review

Parathyroid adenomas may occur within the thyroid, clinically simulating thyroid nodules. Fine-needle aspiration (FNA) of these presumably "thyroid nodules" can lead to misinterpretation of cytomorphological findings because of similarities in cytological features of parathyroid and thyroid lesions. Here, we reported two cases of intrathyroidal parathyroid adenomas. One of them was misinterpreted as thyroid lesions. The other was composed exclusively of oncocytic cells and had a correct cytological diagnosis. In this study, both cases showed a new cytological feature which has not been reported in the literature: many capillaries protruding outside the three-dimensional fragments without epithelial cells around. Diagn. Cytopathol. 2016;44:921-925. © 2016 Wiley Periodicals, Inc.

Chondrosarcoma of the hyoid bone: A diagnostic pitfall in the submandibular region

Chondrosarcoma is a malignant chondroid matrix-producing neoplasm which usually presents in the bones of the pelvis, followed by the proximal femur, proximal humerus, distal femur and ribs. The occurrence of this lesion in the hyoid bone is exceedingly rare, with only a few reported cases, and its diagnosis by fine-needle aspiration cytology (FNAC) in this particular location, to our knowledge, has never been addressed. Furthermore, the sampling of chondroid matrix at this site can pose a diagnostic dilemma with other lesions of the submandibular region. This report describes the clinical, radiologic and cytologic features on FNAC of a chondrosarcoma of the hyoid bone, emphasizing the diagnostic pitfalls of this entity and expanding the cytologic differential diagnosis of tumors of the submandibular region.