International Soc of Bone & Soft Tissue Pathology

Does This Imaging Make Me Look NFATC2? The Value of... : The American Journal of Surgical Pathology journals.lww.com/ajsp/abstract/… Check out the figures and the discussion🔥 🔥 🔥 Does this imaging make me look NFATC2? Props to Dr. Kallen for the title! This paper is for bone loving pathologists! #BSTPath @JHUPath @Greg_Charville @MichaelMichal28 @HopkinsMedicine @mskteachingroom @ctisus @Hopkins_Rad @ISBSTP @reith16

50 F. Large pendulous masses of bilateral thighs. BMI = 65. Diagnosis? Answer ✅ youtu.be/oYqKbtPrF38?si… More clinical pics: kikoxp.com/posts/8185 WSI digital slides: kikoxp.com/posts/8182 #pathology #pathologists #pathTwitter #dermpath #dermatology #dermatologia #dermtwitter

A leiomyosarcoma has extended into colonic mucosa. The arrow indicates a paranuclear vacuole, a characteristic feature of smooth muscle differentiation that is also seen in some gastrointestinal stromal tumors (GISTs), particularly gastric ones. The nuclear atypia is against GIST.

The March 2026 issue of Human Pathology is available online! sciencedirect.com/journal/human-… #pathology #HumPathol #PathTwitter #PathX

This small intestinal histiocytic sarcoma had an NF1 mutation. Shanmugam V, Griffin GK, Jacobsen ED, Fletcher CDM, Sholl LM, Hornick JL. Identification of diverse activating mutations of the RAS-MAPK pathway in histiocytic sarcoma. Mod Pathol. 2019 Jun;32(6):830-843.

Sarcoma represents about 1% of adult cancers and, like many rare cancers, faces delayed diagnoses, limited treatment options, and less research funding. Rare cancers account for nearly 25% of all diagnoses but receive far less investment. At Sarcoma Foundation of America, we’re working to change that by funding research, supporting patients and families, and advocating for better outcomes. Together, we can close the gap and build a future where no one dies from sarcoma. Support our work: buff.ly/C5Olnjy

Cemento-Osseous Dysplasia pathology #pathology

One of my fave pics ever! What are these gorgeous structures?!? What tumor/s do you find them in? Answers ✅ youtu.be/vxF6dEfmv0E?si… What normal #histology structure do they resemble?👉 youtube.com/watch?v=gwPj8G… #pathology #pathologists #pathTwitter #dermpath #dermatology #dermatologia #dermtwitter

Diagnostic IHC Algorithm for Sinonasal Small Round Blue Cell Tumors From Kurt's notes #pathology

Peritoneum, 50y #pathology #patologia #gynpath #gynpathology #gipath #gipathology

Registration is now officially open for our third annual Cleveland Clinic Soft Tissue Pathology Course!! May 14-17, 2026. Live and VIRTUAL options!! 150 brand new cases!! #pathology #softtissue #sarcoma #bstpath #PathTwitter Link: na01.safelinks.protection.outlook.com/?url=http%3A%2… @Williamson_SR @smlungpathguy @JMGardnerMD @MirunaPopescu13 @cebulka26 @evemariecrane @ClevelandClinic @CleClinicNews @CCFPathRes

Atypical lipomatous tumor/well‑differentiated liposarcoma and p16: what pathologists should keep in mind 🧬🧪 Short thread on morphology of atypical lipomatous tumors (ALT/WDL) and how to use p16 wisely in daily sign‑out. Definition 🧾 ALT/WDL is a well‑differentiated adipocytic neoplasm, locally aggressive, with nuclear atypia in fibrous septa and typically associated with MDM2/CDK4 amplification in 12q13‑15. In practice, “large deep lipoma vs ALT/WDL” is one of the most common soft‑tissue dilemmas. Histology: what to look for on H&E 🔬 Architecture Predominantly adipocytic, lobulated lesion, often very similar to a lipoma. Thickened fibrous septa, sometimes hyalinized, traversing the adipose tissue. Cytology Mature adipocytes with mild variation in cell size, usually without striking pleomorphism. Stromal cells in septa with hyperchromatic, enlarged nuclei, sometimes frankly bizarre (“marker cells”). True lipoblasts can be rare or absent and are not mandatory for diagnosis. Special patterns/pitfalls Large lipomas may show fat necrosis, inflammation and fibrosis that mimic “atypical” septa. Intramuscular lipomas, spindle cell lipoma and pleomorphic lipoma may show nuclear enlargement, but in a different, more “dysplastic” than overtly sarcomatous pattern. p16 in practice: when it helps, when it hurts 🧷 What does p16 stain in these tumors? Diffuse, moderate–strong nuclear overexpression is frequent in ALT/WDL and in DDL, in both atypical adipocytes and septal spindle cells. In large series, p16 has been the single most sensitive marker for WDL/DDL, with specificity also high when strict nuclear criteria are used. ⚠️Lipoma vs ALT/WDL⚠️ Several studies show p16 negativity in essentially all deep “ordinary” lipomas, with strong positivity in most ALT/WDL cases. However, lipomas with fat necrosis and secondary/reactive changes may show adipocytic nuclear p16 positivity, lowering specificity, especially in small biopsies. DDL and mimicking sarcomas DDL usually maintains strong/diffuse p16 expression, similar to the WDL component. Other high‑grade sarcomas can also express p16, so the marker is not highly specific in that setting; conversely, some myxofibrosarcomas that are MDM2‑positive can be p16‑negative, which is helpful in retroperitoneal cases. How to interpret p16 in the MDM2/CDK4 panel 🧪 Typical ALT/WDL and DDL scenarios p16+, CDK4+, MDM2+ (moderate/strong, diffuse pattern): classic profile for ALT/WDL/DDL when morphology fits. p16+, CDK4+, MDM2– by IHC: ALT/WDL is still strongly suspected; MDM2 FISH may confirm amplification in a subset of these cases. Patterns that favor benignity p16–, MDM2–, CDK4– in a deep adipocytic tumor with completely bland morphology favors lipoma (while not absolutely excluding ALT/WDL). Tumors that are MDM2–/p16– in series with FISH confirmation have been consistently benign. Key caution points Avoid calling ALT/WDL based on p16 positivity alone, particularly in: Small/incisional biopsies. Lesions with extensive fat necrosis or marked inflammation. Value diffuse, strong nuclear staining in atypical septal cells far more than scattered staining in reactive areas. Take‑home messages NotasPatologia 📌 📌ALT/WDL is, morphologically, a “lipoma with septal atypia”; recognizing those atypical septal cells on H&E is the critical step. 📌p16 is a sensitive marker for ALT/WDL and DDL, but its specificity drops in lipomas with secondary changes and in biopsies. 📌The p16 + CDK4 + MDM2 panel is one of the most useful combinations to separate ALT/WDL/DDL from lipomas and other adipocytic tumors. 📌In a large deep adipocytic tumor of limb or retroperitoneum, diffuse nuclear p16 in atypical septa should strongly raise the suspicion of ALT/WDL, ideally backed up by MDM2 (IHC and/or FISH). 📌Never interpret p16 out of context: morphology, site, size and the full panel still outweigh any single marker. 📚Selected references: Thway et al., Am J Surg Pathol 2012; Kammerer‑Jacquet et al., Hum Pathol 2017; Hedayat et al., Immunopathol Persa 2024; Wu et al., Sci Rep 2025. ⚠️Disclaimer: educational content only; does not replace full pathology reports, guidelines or case‑specific clinical decisions. #Pathology #SoftTissuePathology #Sarcoma #Liposarcoma #ALTWDL #Immunohistochemistry #p16 #NotasDePatologia #MedicalEducation #PathTwitter

After an osteosarcoma diagnosis and leg amputation, Tyler Stowe Robinson lived a full life, with prom, nursing school, time with friends, and even dating. His focus on others inspired his family to fund osteosarcoma research. Read more: osinst.org/blog/tylers-st…

25 M. soft tissue mass in deltoid. Diagnosis? Digital slide: kikoxp.com/posts/8192. Answer ✅ youtube.com/watch?v=cXpecE… #BSTpath #pathologists #pathology #pathTwitter #dermpath

Two classic pics. Tell me the anatomic site, the stain, and the diagnosis. Diagnosis: youtube.com/watch?v=KuXLCi… More info: kikoxp.com/posts/9942. #BSTpath #pathologists #pathology #pathTwitter

Diagnosis: Poorly differentiated synovial sarcoma

Kaposi sarcoma - Tumor (nodular) stage - spindle cells - Sieve-like spaces - mitoses - plasma cells - HHV8+ #medicine #path #dermpath #dermatology #Oncology

Alveolar soft part sarcoma of the breast is quite rare but when it is encountered, one must consider a metastasis (such as from the extremity). innovativesciencepress.com Refs: PubMed PMIDs: 15735860, 18501064, 19021216, 23263847, 30832622

We have an excellent speaker line-up and timely topics for our upcoming annual meeting at USCAP, Sunday March 22. Relationships/distinctions between similar appearing entities? Controversies...you bet! Differences in opinions welcomed...always! Look forward to seeing you there!

Free Soft Tissue Pathology Course - 19 Cases in 3.5 Hours. Video: youtu.be/MA7YUQ-wnHw?si… (for the Oregon #Pathologists Association 2021 annual meeting). #BSTpath #pathology #pathTwitter #dermpath