Undifferentiated pleomorphic sarcoma (UPS) is a high-grade pleomorphic neoplasm with no identifiable line(s) of differentiation using currently available diagnostic techniques. Therefore, it is essentially a diagnosis of exclusion, which requires generous tissue sampling, adequate contextually interpreted immunohistochemistry, and relevant molecular studies. UPS is a common soft tissue sarcoma (historically one of the entities referred to as malignant fibrous histiocytoma (MFH)), which can develop in various organs, but lung involvement is usually due to metastasis. Primary Pulmonary UPS (PPUPS) is exceptionally rare and here we present a 66-year-old man who presented with anemia and weight loss, found to have a 17 cm right lung mass with invasion to the chest wall and diaphragm. Extensive sampling and immunohistochemistry studies failed to reveal any line of differentiation. Upon exclusion of a possible extrapulmonary origin, a diagnosis of PPUPS was rendered. In addition, we reviewed all 84 previously reported cases of PPUPS/PPMFH in the literature since 1979 and summarized the clinical information.

Undifferentiated pleomorphic sarcoma (UPS) is a high-grade pleomorphic neoplasm with no identifiable line(s) of differentiation using currently available diagnostic techniques. Therefore, it is essentially a diagnosis of exclusion, which requires generous tissue sampling, adequate contextually interpreted immunohistochemistry, and relevant molecular studies. UPS is a common soft tissue sarcoma (historically one of the entities referred to as malignant fibrous histiocytoma (MFH)), which can develop in various organs, but lung involvement is usually due to metastasis. Primary Pulmonary UPS (PPUPS) is exceptionally rare and here we present a 66-year-old man who presented with anemia and weight loss, found to have a 17 cm right lung mass with invasion to the chest wall and diaphragm. Extensive sampling and immunohistochemistry studies failed to reveal any line of differentiation. Upon exclusion of a possible extrapulmonary origin, a diagnosis of PPUPS was rendered. In addition, we reviewed all 84 previously reported cases of PPUPS/PPMFH in the literature since 1979 and summarized the clinical information.

In adults, B-lymphocytes comprise approximately 10% of circulating lymphocytes. The majority of peripheral B cells are B2 cells ("Mature" B-cells), which function as part of the humoral adaptive immune system. B1 cells ("Innate-like" B cells) are another sub-class of B lymphocytes, considered as innate immune cells with a characteristic phenotype (CD20+, CD27+, CD43+, CD70-, CD11b+, sIgM++, sIgD+) which can be divided into two subtypes; B1a (CD5+): spontaneously produce broadly reactive natural IgM, and B1b (CD5-): can generate T-cell independent, long-lasting IgM. There is very limited data available, indicating a correlation between allogeneic bone marrow transplantation and an increase in B1a cells. Here we present a case of a 17-year-old female with homozygous sickle cell disease (HbSS disease) who underwent hematopoietic stem cell transplant (HSCT). Approximately seven months post-transplant, she was found to have 16% immature mononuclear cells on complete blood count (CBC)-differential report. A follow-up peripheral blood flow cytometry showed that these cells were polyclonal CD5+/CD20+ B-cells, and comprised 66% of lymphocytes. Further workup and follow up failed to reveal any lymphoproliferative disorders. It is important not to misdiagnose these cells as an atypical CD5+ lymphoproliferative disorder. The presence of B1a cells has not been widely reported in non-neoplastic post-stem cell transplanted patients. This case also adds to and expands our knowledge regarding the presence of increased circulating B1a cells after stem cell transplant in a patient with no history of hematological malignancy.

Undifferentiated carcinoma of the pancreas with osteoclast-like giant cells (UCOGCs) is an extremely rare morphologically and clinically distinct variant of pancreatic ductal adenocarcinoma (PDAC), exhibiting a characteristic component of reactive osteoclast-like giant cells admixed with neoplastic mononuclear cells. Sommers and Meissner first described it in 1954 as an "unusual carcinoma of the pancreas". Later it acquired many different names. In 2010, the WHO classified these tumors as a variant of PDAC under the heading of "undifferentiated carcinoma with osteoclast-like giant cells". Here we describe the first case of pancreatic mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) composed of UCOGC and pancreatic neuroendocrine tumor (NET), which occurred in a 78-year-old man with biliary colic and pancreatitis. The mass did not respond to the chemotherapy, and he soon developed liver metastasis from the NET component, and unfortunately, the patient passed away 10 months later. Since UCOGC is extremely rare, and its association with NET has not been reported yet, our case expands the knowledge regarding its unusual presentation and poor prognosis.

Introduction and importance

Functioning pancreatic neuroendocrine tumors (pNETs) that express pancreatic polypeptide-PPomas-do not yet have a pathognomonic clinical syndrome associated with them due to their overall rarity and diverse symptoms. Moreover, in patients with MEN1, the often multifocal nature of pNETs presents a unique clinical issue.

Case presentation

We report a case of a 22-year-old man with a known MEN1 gene mutation who was suffering from severe diarrhea (7-8 bowel movements per day) and was found to have only elevated PP levels on biochemical work-up. Ga68-DOTATATE PET/CT showed multifocal tumors in the body and tail of the pancreas that were not evident on contrast-enhanced CT. The patient underwent a successful laparoscopic radical antegrade modular pancreatosplenectomy (RAMP) and recovered well post-operatively with complete resolution of his diarrhea. Immunohistochemistry showed multiple pure PPomas.

Clinical discussion

This case highlights the unique propensity for multifocal disease in patients with MEN1 mutations and the utility of functional imaging by somatostatin analogs, i.e., Ga68-DOTATATE PET/CT, in order to perform oncologic laparoscopic pancreatic resections.

Conclusion

PPomas in the setting of MEN1 mutations are a unique clinical entity due to their diverse associated clinical syndromes and propensity for multifocal disease.

Traditional histology relies on processing and physically sectioning either frozen or formalin-fixed paraffin-embedded (FFPE) tissue into thin slices (typically 4-6 μm) prior to staining and viewing on a standard wide-field microscope. Microscopy using ultraviolet (UV) surface excitation (MUSE) represents a novel alternative microscopy method that works with UV excitation using oblique cis-illumination, which can generate high-quality images from the cut surface of fresh or fixed tissue after brief staining, with no requirement for fixation, embedding and histological sectioning of tissue specimens. We examined its potential utility in dermatopathology. Concordance between MUSE images and hematoxylin and eosin (H&E) slides was assessed by the scoring of MUSE images on their suitability for identifying 10 selected epidermal and dermal structures obtained from minimally fixed tissue, including stratum corneum, stratum granulosum, stratum spinosum, stratum basale, nerve, vasculature, collagen and elastin, sweat glands, adipose tissue and inflammatory cells, as well as 4 cases of basal cell carcinoma and 1 case of pseudoxanthoma elasticum deparaffinized out of histology blocks. Our results indicate that MUSE can identify nearly all normal skin structures seen on routine H&E as well as some histopathologic features, and appears promising as a fast, reliable and cost-effective diagnostic approach in dermatopathology.

Ochronosis is a cutaneous disorder caused by the accumulation of phenols, either endogenously as homogentisic acid in patients with alkaptonuria (autosomal recessive disorder with deficiency of the enzyme homogentisic acid oxidase), or exogenously in patients using phenol products such as topical creams containing hydroquinone or the intramuscular application of antimalarial drugs. Exogenous ochronosis (EO) typically affects the face and was reported in patients with dark skin such as Black South Africans or Hispanics who use skin-lightening products containing hydroquinone for extended periods. Recently more cases have been reported worldwide even in patients with lighter skin tones, to include Eastern Indians, Asians, and Europeans. However, just 39 cases of EO have been reported in the US literature from 1983 to 2020. Here we present two cases; a 69 and a 45-year-old female who were seen for melasma, given hydroquinone 4% cream daily and tretinoin 0.05%. Both patients noticed brown spots on their cheeks, which progressively enlarged and darkened in color. The diagnosis of ochronosis was confirmed by characteristic histopathological features on the punch biopsy. Unfortunately, neither patient responded to multiple treatments (to include, tazarotene 0.1% gel and pimecrolimus ointment, topical corticosteroids, and avoidance of hydroquinone containing products). We also present a case of classic (endogenous) ochronosis in a patient with alkaptonuria to picture the histological similarities of these two entities. EO is an important clinical consideration because early diagnosis and treatment may offer the best outcome for this notoriously refractory clinical diagnosis.

Arteriovenous malformation (AVM) is a rare lesion in the uterus, which can lead to abnormal uterine bleeding. While AVM has been described in other organs in the literature, there is a paucity of pathology reports of the AVM in uterus. On gross examination, the uterus was markedly enlarged and partly distorted with a pedunculated solid mass, which on the cut surface showed multiple well-circumscribed hemorrhagic cysts ranging from 0.1 to 4.0 cm in size. Microscopically, they were malformed dilated vascular structures containing organized thrombi. We present this case of uterine AVM with gross and microscopic findings, which can serve as a crucial reminder for pathologists to keep in the differential diagnoses as a potential cause of abnormal uterine bleeding.