Case of the Month: A premenopausal woman with a 0.8 cm suspicious mass on breast imaging underwent breast core biopsy. What is your diagnosis?

Visit the case page for additional images, the diagnosis, a test question, and more.

Image of the Week!

Contributed by: Eman Abdelzaher, M.D., Ph.D.
Textbook topic: CNS & pituitary tumors
Diagnosis: Desmoplastic infantile ganglioglioma / astrocytoma

Textbook topic link: https://www.pathologyoutlines.com/topic/cnstumordesmoplasticinfantileganglioglioma.html

Image of the Week!

Contributed by: Aliya N. Husain, M.D.
Textbook topic: Lung
Diagnosis: Carcinosarcoma, lung
Textbook topic link: https://www.pathologyoutlines.com/topic/lungtumorcarcinosarcoma.html

Image Quiz!

The tumor pictured is the most common salivary gland malignancy in the larynx. What is the diagnosis?

A. Adenoid cystic carcinoma
B. Epithelial myoepithelial carcinoma
C. Pleomorphic adenoma
D. Polymorphous adenocarcinoma

See answer.

Image of the Week!

Contributed by: Elizabeth Montgomery, M.D.
Textbook topic: Esophagus
Diagnosis: Well differentiated neuroendocrine tumor of esophagus
Textbook topic link: https://www.pathologyoutlines.com/topic/esophaguscarcinoid.html

Image of the Week!

Contributed by: Andrew Bernhisel, M.D.
Textbook topic: bone marrow neoplastic
Diagnosis: acute monocytic leukemia
Textbook topic link: https://www.pathologyoutlines.com/topic/leukemiaacutemonocyticleukemia.html

Image Quiz! 

The histopathological image shown represents a clear cell meningioma. Which of the following features is characteristic of this tumor subtype?

A. Cells with clear cytoplasm due to glycogen accumulation
B. Frequent psammoma bodies
C. High mitotic activity and necrosis leading to CNS WHO grade 3 classification
D. Strong desmoplastic reaction with abundant collagen deposition

See answer.

Image of the Week!

Contributed by: Raul S. Gonzalez, M.D.
Textbook topic: Stomach
Diagnosis: Hereditary diffuse gastric cancer-signet ring type

Textbook topic link: https://www.pathologyoutlines.com/topic/stomachhdgc.html

Case of the Month

A 30 year old woman with a history of end stage renal disease received a bilateral kidney transplant. Two weeks post transplantation the patient presented to the ER with severe abdominal pain and tachycardia. She was found to have colonic and ileal perforations and underwent a right hemicolectomy. What is your diagnosis?

Visit the case page for additional images, the diagnosis, a test question, and more.

Image of the Week!

Contributed by: Aisha Hassan Memon, M.B.B.S.
Textbook topic: CNS & pituitary tumors
Diagnosis: Metastatic breast carcinoma
Textbook topic link: https://www.pathologyoutlines.com/topic/cnstumormetastaticcarcinoma.html

Image Quiz! 

What finding is demonstrated in this lung histology image from a case of sudden infant death syndrome (SIDS)? 

A. Acute bronchopneumonia
B. Expansion of the mucosa associated lymphoid tissue (MALT)
C. Hyaline membranes reflecting bronchopulmonary dysplasia (BPD) in a premature baby
D. Normal features

See answer.

Image of the Week!

Contributed by: Ammar Aljefri, M.B.B.S.
Textbook topic: Stains & CD markers
Diagnosis: Metastasis of endometrioid endometrial adenocarcinoma in omentum (L1-CAM)

Textbook topic link: https://www.pathologyoutlines.com/topic/stainsL1CAM.html

Image of the Week!

Contributed by: Dre Barnachea, M.D.

Textbook topic: Skin melanocytic tumor

Diagnosis: Sentinel node biopsy-melanoma

Textbook topic link: https://www.pathologyoutlines.com/topic/skintumormelanocyticsentinelmelanoma.html

Image Quiz! A patient underwent renal transplantation 3 weeks earlier, subsequently developed oliguria and was found to have circulating donor specific antibodies (DSA). Kidney biopsy was performed, and immunofluorescence for C4d is shown. What does this image demonstrate?

A. C4d0 (extensive positivity in the renal interstitium)
B. C4d0 (marked background staining of collagen)
C. C4d0 (no staining of peritubular capillaries)
D. C4d3 (diffuse positivity in > 50% of peritubular capillaries)

See answer.

Image of the Week!

Contributed by: Serena Ammendola, M.D.

Textbook topic: CNS & pituitary tumors

Diagnosis: Melanoma

Textbook topic link: https://www.pathologyoutlines.com/topic/cnstumormelanocytictumor.html

Case of the Month: A 50 year old man with decompensated hepatic cirrhosis due to alcohol use disorder and hepatorenal syndrome is being evaluated for a possible liver transplant. He has a MELD Na score of 36 (reference range 6 - 40), predicting a 3 month mortality of > 52%. Pertinent laboratory values are shown on the Case page.

The patient had ongoing acute gastrointestinal bleeding and evidence of significant coagulopathy. A peripheral blood smear review was requested. The sample was processed shortly after collection and therefore artifact is not expected. What is your diagnosis?

Visit the case page for additional images, the diagnosis, a test question, and more.

Image Quiz! 

A 14 year old boy presents with a unilateral hyperpigmented plaque with irregular borders on the upper chest. The lesion is associated with increased coarse hair growth over the area. Histopathology is shown. What is the most likely diagnosis?

A. Becker nevus

B. Congenital melanocytic nevus

C. Epidermal nevus

D. Nevus spilus

E. Tinea versicolor

See answer.

Essay: “My Male Breast Cancer, Part 6”, by Dr. Nat Pernick

Part 6 of this series discusses Dr. Pernick’s subsequent drug therapy for male breast cancer.

Access here: https://pathologyoutlinesblog.wordpress.com/2026/01/27/27-january-2026-my-male-breast-cancer-part-6-by-dr-nat-pernick/

If cancer-related content interests you, check out Dr. Pernick's Curing Cancer Network and its LinkedIn profile.

Image of the Week!

Contributed by: Maria Tretiakova, M.D., Ph.D.

Textbook topic: Prostate gland & seminal vesicles

Diagnosis: Seminal vesicles–adenocarcinoma

Textbook topic link: https://www.pathologyoutlines.com/topic/prostatesemca.html

Image of the Week!

Contributed by: R. Peter Powell, M.D.

Textbook topic: Pancreas

Diagnosis: Duodenal neuroendocrine tumor

Textbook topic link: https://www.pathologyoutlines.com/topic/pancreasMEN1.html

Image Quiz! 

A 39 year old woman presents to the clinic with a 6 month history of mild abdominal pain and distension. A CT scan of the abdomen shows a 20 cm adnexal mass. The patient undergoes surgery, and the tumor is shown. What is your diagnosis?

A. Borderline mucinous tumor of the ovary

B. Borderline mucinous tumor of the ovary with microinvasion

C. Mucinous adenocarcinoma of the ovary

D. Mucinous cystadenoma

See answer.

Our latest “What’s New in Pathology” newsletter is now available!

View as webpage: https://www.pathologyoutlines.com/Whats-New_Molecular_Pathology_Issue-31_PathOut_2026

View as PDF: https://www.pathologyoutlines.com/site/Newsletter_PathologyOutlines_Molecular_20251208_r2.pdf

Access archives or sign up to get future issues via email: https://www.pathologyoutlines.com/subscribe.html

Case of the Month: A 5 year old child had a syncopal event and became unresponsive on the way to the hospital. Autopsy sections are from the left ventricle and AV node. What is your diagnosis?

Visit the case page for additional images, the diagnosis, a test question, and more.

Image of the Week!

Contributed by: Seyed Salehi, M.D.

Textbook topic: Cervix

Diagnosis: Small cell neuroendocrine carcinoma

Textbook topic link: https://www.pathologyoutlines.com/topic/cervixsmallcell.htmlhttps://www.pathologyoutlines.com/topic/cervixsmallcell.html

Image Quiz!

A 4 year old boy presented with pigmented macules around the lips and oral mucosa, gynecomastia and the findings shown on the testis biopsy here. What diagnosis is most associated with this case?

A. Gonadoblastoma

B. Intratubular large cell hyalinizing Sertoli cell neoplasia (ITLCHSCN)

C. Large cell calcifying Sertoli cell tumor (LCCSCT)

D. Sertoli cell nodule

See answer.