Rhabdomyomatous Mesenchymal Hamartoma: Report of 4 Cases With Histochemical and Immunohistochemical Findings and Emphasis on Potential Pitfalls.

Rhabdomyomatous mesenchymal hamartoma (RMH) typically presents as a congenital midline head and neck cutaneous polyp in infants. Perianal and mucocutaneous lesions have been reported, and recently, acquired adult-onset variants have been proposed. This makes the true prevalence, etiopathogenesis, and clinicopathologic distribution and classification of RMHs in children compared with those in adults uncertain. We performed a retrospective review to highlight the salient histopathologic, histochemical, and immunohistochemical features in RMHs and to emphasize their specific clinicopathologic criteria to avoid diagnostic pitfalls. We found 4 (0.3%) infants [2 female infants and 2 male infants, average age: 4 months] with mental, nasal, lingual, and perianal midline RMHs (average size: 1.0 cm) of 1303 patients with cutaneous polypoid lesions. Three were isolated, and 1 was associated with Goldenhar syndrome. The cutaneous polyps demonstrated intermixed skeletal muscle, adipose, and fibrocollagenous core stroma that extended into the dermis and around the dermal appendages. The lingual lesion demonstrated skeletal muscle and fibrocollagenous stroma with prominent nerve bundles and little adipose tissue. All showed interstitial loose mesenchyme. Masson trichome demarcated the triphasic stromal components. Alcian blue demonstrated the loose myxoid mesenchyme. Elastic van Gieson did not show elastic fibers. Desmin demonstrated the skeletal muscle bundles, S100 highlighted the adipose tissue lobules and the nerve bundles, and CD34 displayed the mesenchymal stroma. Ki67 showed a low proliferation index in the loose mesenchyme. Smooth muscle actin did not reveal smooth muscle bundles, but with CD31, they highlighted the thick blood vessels. CD117 revealed prominent mast cells. From our retrospective review series, 4 cases that originally diagnosed as RMHs were excluded. Likewise, we found some examples of the reported cases in the English literature that might have been mistaken for RMHs. This is because they did not fulfill the diagnostic clinicopathologic criteria. RMH constitutes a rare entity with specific clinicopathologic features. Most lesions are isolated. Some are associated with congenital anomalies and syndromes. Strict clinicopathologic diagnostic criteria should be applied to avoid mislabeling look-alike lesions for RMHs.

Nevus lipomatosus superficialis: A series of six cases.

Nevus lipomatosus still imposes diagnostic, categorization, and etiologic challenges. Even though an intradermal adipose tissue is a histopathologic prerequisite, the lesions are clinically divided into classic multiple forms and a solitary variant, which some consider a separate so-called lipofibroma clinicopathologic entity. This further complicates the true prevalence, classification and etiopathogenesis of nevus lipomatosus. Case reports and series studies have reflected either consistent or variable and sometimes conflicting clinicopathologic findings. A few have reported electron microscopic findings. Immunohistochemistry is lacking. We report two multiple and four solitary forms of nevus lipomatosus in six patients, highlighting their salient histopathologic features and immunohistochemical profile. Both forms showed intradermal groups of perivascular S100+ lipogenic and CD34+ mesenchymal cells intermixed with scattered CD1a+ and FXIIIa+ dendrocytes, CD3 lymphocytic and CD117 mast cells in a fibromyxoid milieu. Epidermal nevoid and comedonal follicular alterations, attenuated dermal connective tissue and adnexal structures were variably present in both forms. We compared our findings with seven series of studies reporting classic and solitary forms. Both forms showed similar histopathologic findings, comparable clinicopathologic features, predominantly pelvic, and shoulder girdle distribution patterns in bimodal age onsets. Even though some lipomatous skin lesions clinically and histopathologically overlap with nevus lipomatosus, certain findings are helpful distinguishing features. Small intradermal islands of lipocytic fibroplasia have characteristic perivascular milieu that may function as a niche of preadipose CD34 mesenchymal stem cells. They are most likely represented in the dermis of the pelvic and shoulder areas in certain individuals prone to maintain these embryonic reservoirs, which are clinically manifested at different ages. Some may have unifocal or multifocal residues reflecting multiple and solitary forms.

Synovial Lipomatosis: Histopathologic Features in a Series of Five Cases.

Synovial lipomatosis is a controversial entity of uncommon intraarticular joint lesions. Most studies focused on radiological findings and surgical resection modalities. Pathologic findings were limited to case reports. Detailed descriptions of the histopathologic features are lacking. We aim to highlight the salient histopathologic features of synovial lipomatosis. We performed a retrospective review study over 15 years retrieving cases of synovial lipomatosis. We found 5 patients (age range: 8-78, average age: 50 years, male to female ratio: 4:1) demonstrating unilateral synovial lipomatosis out of 241 (2.0%) patients with knee joint lesions. Four patients had osteoarthritis. One patient was obese. The resected specimens showed synovial hyperplasia, surface fibrin, hemosiderin pigment, microcalcifications, lymphoplasmacytic infiltrates, lymphoid aggregates, stromal fibrotic, degenerative, and metaplastic alterations shared by other synovitis related changes. Consistent features included abundant adipocytic components, surface adipocytes, prominent large vessel vasculatures, plasma cells, and dense perivascular lymphocytic cuff-like infiltrates. One patient demonstrated superimposed sarcoid-type epithelioid granulomas. A distinct fibrous band separated the lesional tissue from the underlying normal fatty tissue. Synovial lipomatosis predominates in older males with degenerative joint conditions with a second peak in children and adolescents. Obesity is not a risk factor. Some histopathologic features help distinguish synovial lipomatosis from look-alike joint lesions. The findings may suggest an angiolipomatous hamartomatous growth or an exaggerated synovial reaction inducing florid subsynovial stromal proliferative, metaplastic, and degenerative changes. Regardless of its etiopathogenesis, pathologists have a role in confirming the diagnosis and ensuring a complete arthroscopic synovectomy by assessing the presence of the fibrous septa.

Rectal Gastrointestinal Stromal Tumors.

Rectal gastrointestinal stromal tumors (GISTs) are rare types of tumors, but the incidence is increasing, and we now know more about the pathogenesis and management of rectal GIST. The main goal is to resect the tumor with negative microscopic margins. With the development of neoadjuvant Imatinib therapy, preoperative reduction in tumor size has become possible, thus introducing the chance for anus-preserving surgery, with better quality of life. We present a case of a 55-year-old female who presented to the emergency department with complaints of bleeding per rectum, abdominal pain, and pain on defecation. A 6-cm mass was detected during the rectal examination and a biopsy confirmed the diagnosis of GIST. The patient was given neoadjuvant imatinib chemotherapy for four months followed by trans-anal resection of the mass. The procedure was done successfully, and she received further adjuvant imatinib for a course of three years. Follow-up by magnetic resonance imaging and a colonoscopy after two years showed no recurrence. The patient is living healthily and doing well.

Histopathologic Findings of Button Battery-Related Changes in a Perforated Meckel's Diverticulum: Report of Three Cases.

Background: A button battery can cause perforation of Meckel's diverticulum if sequestered in this blind ending bowel segment. Reported cases focused on clinical manifestations, management options, radiologic and intraoperative findings. We highlight the histopathologic features in perforated Meckel's diverticula due to ingested button batteries. Case report: Three toddlers presented with perforated Meckel's diverticula after button battery ingestion. Histologic examination of the diverticula showed multiple burn-like mucosal ulcerations and liquefactive wall perforations of the tips, associated with prominent siderotic pigment deposits and calcifications. There were various residual materials with variable staining patterns in the luminal debris, necrotic tissue and adjacent to submucosal blood vessels. Conclusion: There is accelerated deposition of iron and calcium associated with button batteries.

Extranodal Mesenteric Follicular Dendritic Cell Sarcoma Expressing Keratin Antigens: What Pitfalls Initiate Diagnostic Clues.

Extranodal follicular dendritic cell sarcomas are infrequent diagnostically challenging tumors. Because of their rarity, heterogeneous histomorphologic features and variable histologic grades a significant number of extranodal lesions are prone to be misdiagnosed. Even though they have a characteristic immunoprofile, expression of a range of nonspecific markers is well documented. Even though they are typically negative for keratins, few authors have reported lesions expressing keratin. Keratin expressing tumors are more likely to be misinterpreted by pathologists further deterring their inclusion in the differential diagnosis. We report an intraabdominal mesenteric follicular dendritic cell sarcoma in a 44-year-old male that immunophenotypically expressed keratin antigens. The lesion showed a high-grade pleomorphic epithelioid appearance and the initial differential diagnosis included lymphoma, sarcomas, melanoma, and carcinomas. Follicular dendritic cell sarcoma was not considered. Expression of epithelial membrane antigen and keratin further deterred the diagnosis which was reached only after extensive use of immunomarkers. The tumor cells expressed CD21, CD23, and D2-40. Morphologically, the tumor showed some thymoma-like features with occasional TDT-expressing background T-lymphocytes. These features were hints to reconsider our differential diagnosis to include follicular dendritic cell tumors. Awareness of this aberrant staining of epithelial immunomarkers and attention to certain clues should encourage pathologists to consider this entity. Speculative assumptions may explain this unusual keratin expression in some lesions. The histomorphologic and immunohistochemical heterogeneity may suggest different variants and grades of follicular dendritic cell sarcomas. The prevalence, importance, and histogenesis of keratin expression in follicular dendritic cell sarcomas warrant further studies.

Giant appendiceal mucocele as a first manifestation in a patient with silent ulcerative colitis: A case report.

Appendiceal mucocele (AM) is a rare lesion found in only 0.3% of all appendectomies and it is characterized by distention of the appendix by the accumulating intraluminal mucinous material. Four main histopathological subtypes of appendiceal mucocele has been described including: retention cyst, mucosal hyperplasia, mucinous cystadenoma, and cystadenocarcinoma. We report a case of 48-year-old middle eastern female, previously healthy, presented to the primary health center with right iliac fossa discomfort, and referred to our hospital for further evaluation. Contrast enhanced computed tomography of the abdomen and pelvis and focused ultrasonography over the right iliac fossa showed the characteristic CT and sonographic appearance of appendiceal mucocele. An additional incidental note of lack of colonic haustral pattern involving the rectum and descending colon was noted on abdominal CT raising the suspicion of Ulcerative Colitis which was then confirmed by colonoscopy and histopathology. Although no causal relationship between appendicular mucocele and inflammatory bowel disease has been established yet and few case reports had reported appendicular mucocele in patients with ulcerative colitis, close surveillance in these patients, and early recognition of the characteristic imaging features is crucial in preventing dreadful complications like pseudomyxoma peritonei.

Leiomyosarcoma of the Vulva Mimicking as Chronic Bartholin Cyst: A Case Report.

Smooth muscle neoplasms of the vulva are rare, and when localized in the Bartholin's gland, it can be mistaken as a benign lesion leading to a delay in diagnosis. We report a case of leiomyosarcoma of the Bartholin's gland in a 63-year-old postmenopausal woman, which clinically mimicked a chronic Bartholin's gland cyst. This case report emphasizes the importance of suspecting malignancy in any vulvar lesion in women of postmenopausal age, despite its location and asymptomatic appearance. A prompt, careful evaluation with adequate clinical judgment will help to manage such cases efficiently.

A Serrated Hyperplastic Colonic Polyp of the Urinary Bladder.

Intestinal metaplasia of the urinary bladder can occur within the surface urothelium due to chronic irritation in repaired exstrophic urinary bladder. Colonic villous adenomas and tubulovillous adenomas with high-grade dysplasia and associated adenocarcinoma have been reported in adult patients with a history of augmented exstrophic bladder. To our knowledge, we report the first example of a nonadenomatous serrated hyperplastic colonic polyp in an elderly patient with a history of exstrophic bladder.

Laryngeal sarcomas: A case series of 5 cases.

Primary sarcomas of the larynx are rare and miscellaneous. The most common is chondrosarcoma. Other sarcomas are very rare. Sarcomas can have heterogeneous morphologic features of spindle, small round, epithelioid, pleomorphic and giant cells. Laryngeal sarcomas may mimic carcinomas, lymphomas, small cell carcinoma, mesothelioma and melanoma. This imposes diagnostic challenges for unfamiliar pathologists particularly in small laryngeal biopsies. Our aim was to study the different types of sarcomas that can involve the larynx in our institution, to investigate their diagnostic challenges and potential pitfalls and to find helpful histologic clues to avoid misinterpretation and missed diagnosis. We performed a retrospective review study over 13 years. We retrieved 5 cases of laryngeal sarcomas. They included Kaposi sarcoma, low-grade chondrosarcoma, epithelioid angiosarcoma, polypoid leiomyosarcoma and small cell osteosarcoma. The age range was between 32 and 74 years with an average age of 52 years. The male to female ratio was 3:2. The Kaposi sarcoma and chondrosarcoma were correctly diagnosed. The angiosarcoma was initially missed as recurrent carcinoma. The leiomyosarcoma was initially inferred as polypoid sarcomatoid squamous cell carcinoma. The small cell osteosarcoma initiated the differential diagnosis of high-grade lymphoma, small cell carcinoma, undifferentiated carcinoma, Ewing sarcoma and rhabdomyosarcoma. An implementation of a panel of immunohistochemical markers guided by certain histomorphologic clues was helpful to make the correct diagnosis. Pathologists should be aware of the morphologic spectrum and different growth patterns of laryngeal sarcomas. Immunohistochemistry studies are essential. Correct diagnosis, classification and grading of laryngeal sarcomas are clinically important for the prognosis and appropriate management of patients.

Adrenocortical Oncocytic Carcinoma and Papillary Thyroid Carcinoma Incidentally Detected in an Asymptomatic Patient by F-18 FDG PET/CT.

F-18 FDG is the most widely used tracer in molecular imaging and it is applied for many purposes mainly in malignant diseases. Incidental finding are common in FDG-PET/CT imaging and includes benign and malignant lesions. Among the rare tumors , adrenal oncocytomas are uncommon findings and incidental findings of thyroid malignancies are not rare. Oncocytoma is a rare adrenocortical tumor and majority of bulky adrenal tumors are benign with uncertain incident of malignancy. In this study, we are reporting a 37-year-old man with two incidental malignancies detected by FDG-PET-CT. He has no symptoms has no blood and hormonal abnormalities. The scan demonstrated intense heterogeneous FDG uptake within the bulky oval shaped lesion in the left adrenal gland. Accordingly, open adrenalectomy was performed and diagnosis of adrenocortical carcinoma oncocytic type was established. Furthermore, a focal FDG uptake was identified in the right thyroid lobe and histopathology findings were consistent with well-differentiated papillary thyroid cancer. FDG plays a great role in identifying primary rare lesions and also detection of incidental findings at unexpected sites.

Unusual benign polypoid and papular neoplasms and tumor-like lesions of the vulva.

We aimed to investigate the prevalence and spectrum of unusual benign neoplasms and tumor-like lesions presenting as vulvar polyps and papules, to study their clinical, pathologic, hormonal, and developmental features and whether they have important associations with other pathologic lesions or clinical diseases. We conducted a retrospective review study of 115 vulvar specimens over 7 years. Common lesions, for example, fibroepithelial polyps, skin tags, papillomas, abscesses, viral warts and common cysts, were excluded. We found 21 cases (18%) with uncommon benign vulvar lesions. They included 7 epithelial cysts, 3 vascular lesions, 3 glandular neoplasms, 3 endometrioses, 1 caruncle, 1 pilonidal sinus, 1 prolapsed urethra, 1 seborrheic keratosis, and 1 granular cell tumor. The age range was between 1 and 64 years with a mean age of 33 years. Most (86%) were 2.5 cm or less. Many were asymptomatic incidental pathologic findings that can be missed clinically. Nine cases have important clinical associations or coexisting incidental pathologic lesions. Some lesions demonstrated hormone receptors. Some were clinically confused with fibroepithelial polyps, abscesses, warts, melanocytic lesions, and tumors. In conclusion, although the vulva is a small compartment, its developmental and histologic complexity can result in a variety of unusual and rare benign polypoid and papular lesions, some unique to the vulva, which might present diagnostic challenges to the clinicians and pathologists. In addition, many bear controversy regarding their histogenesis and origin of development in the vulva.

Benign anal and perianal polypoid neoplasms and tumor-like lesions.

Mesenchymal anal and perianal tumors are relatively uncommon. The majority are malignant. Benign mesenchymal anal tumors are rare. Some are common stromal neoplasms, but with the rare presentation as anal polyps. Other lesions are rare, but unique to the anal/perianal region. Common keratinous cysts might uncommonly present as anal polyps, while other rare cysts are unique to the anogenital region. A retrospective review study of 493 anal and perianal specimens conducted over seven years showed twenty cases (4.0%) of benign anal polypoid lesions. We excluded the usual fibroepithelial polyps, anal tags, papilla, hemorrhoids and warts. We found six cysts, three lipomas, two papillary hidradenomas, two melanocytic nevi, one hamartoma, one xanthogranuloma, one seborrheic keratosis, one hematoma, one fibrous histiocytoma, one granular cell tumor and one lymphangioma. The male to female ratio was 1.5:1. They were found in adults (mean age 37.8 years) and in infants (mean age 2.4 years). In general, they were smaller than 2 cm. They were either asymptomatic or presented with anal pain, bleeding or lumps. Some were clinically confused with the more common non-neoplastic anal tags, hemorrhoids and fibroepithelial polyps/papilla. A variety of common and rare benign lesions might present as anal polyps with important surgical and pathologic challenges and implications.

Mesoappendiceal and periappendiceal lesions.

Lesions of the mesoappendix are rare. The majority are benign and incidental pathologic findings. They rarely present clinically or radiologically. A spectrum of infectious, tumor-like, and neoplastic lesions can involve the mesoappendix and the periappendiceal tissue. Pathologists usually pay little attention to the gross examination of the mesoappendix in appendectomy specimens in comparison to the appendix itself. This could lead to a missed opportunity to identify mesoappendiceal lesions, despite being rare, but some are clinically important for the patient's management. Pathologists should perform careful gross examination and sectioning of the mesoappendix. A retrospective review study of 4371 appendectomy specimens over four years showed eight cases (0.18%) with a variety of mesoappendiceal and periappendiceal lesions. Most (five cases) were benign incidental pathologic findings (lymph nodes with reactive follicular hyperplasia, ectopic decidua, infarcted epiploica and peritoneal cyst), one case was a rare occurrence (inflammatory fibroid tumor), and few others (two cases) were clinically important findings (tuberculosis and schistosomiasis). They were more commonly found in young adult males with a male to female ratio of 7:1.