A 49-year-old woman presents to her physician with complaints of breast swelling and redness of the skin over her right breast for the past 1 month. She also mentions that the skin above her right breast appears to have thickened. She denies any pain or nipple discharge. The past medical history is significant for a total abdominal hysterectomy at 45 years of age. Her last mammogram 1 year ago was negative for any pathologic changes. On examination, the right breast was diffusely erythematous with gross edema and tenderness and appeared larger than the left breast. The right nipple was retracted and the right breast was warmer than the left breast. No localized mass was palpated. Which of the following statements best describes the patient’s most likely condition?

The inflammation is due to obstruction of dermal lymphatic vessels.

It shows predominant lymphatic spread.

The lesion expresses receptors for estrogen and progesterone.

The lesion is due to Streptococcal infection.

A 62-year-old woman presents to her physician with a painless breast mass on her left breast for the past 4 months. She mentions that she noticed the swelling suddenly one day and thought it would resolve by itself. Instead, it has been slowly increasing in size. On physical examination of the breasts, the physician notes a single non-tender, hard, and fixed nodule over left breast. An ultrasonogram of the breast shows a solid mass, and a fine-needle aspiration biopsy confirms the mass to be lobular carcinoma of the breast. When the patient asks about her prognosis, the physician says that the prognosis can be best determined after both grading and staging of the tumor. Based on the current diagnostic information, the physician says that they can only grade, but no stage, the neoplasm. Which of the following facts about the neoplasm is currently available to the physician?

The tumor cells exhibit marked nuclear atypia.

The tumor invades the pectoralis major.

The tumor has spread via blood-borne metastasis.

The tumor has not metastasized to the contralateral superior mediastinal lymph nodes.

The tumor has metastasized to the axillary lymph nodes.

Two weeks after undergoing low anterior resection for rectal cancer, a 52-year-old man comes to the physician because of swelling in both feet. He has not had any fever, chills, or shortness of breath. His temperature is 36°C (96.8°F) and pulse is 88/min. Physical examination shows a normal thyroid and no jugular venous distention. Examination of the lower extremities shows bilateral non-pitting edema that extends from the feet to the lower thigh, with deep flexion creases. His skin is warm and dry, and there is no erythema or rash. Microscopic examination of the interstitial space in this patient's lower extremities would be most likely to show the presence of which of the following?

Neutrophilic, protein-rich fluid

Lymphocytic, hemosiderin-rich fluid

Protein-rich, glycosaminoglycan-rich fluid

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

A 59-year-old woman presents to her primary care provider with a 6-month history of progressive left-arm swelling. Two years ago she had a partial mastectomy and axillary lymph node dissection for left breast cancer. She was also treated with radiotherapy at the time. Upon further questioning, she denies fever, pain, or skin changes, but reports difficulty with daily tasks because her hand feels heavy and weak. She is bothered by the appearance of her enlarged extremity and has stopped playing tennis. On physical examination, nonpitting edema of the left arm is noted with hyperkeratosis, papillomatosis, and induration of the skin. Limb elevation, exercise, and static compression bandaging are started. If the patient has no improvement, which of the following will be the best next step?

Vascularized lymph node transfer

Lymph node groups and clinical significance for USMLE Step 2 CK: High-Yield Anatomy Lessons

Lymph Node Anatomy - The Body's Filters

Structure: Encapsulated organs with three main zones: cortex, paracortex, and medulla.
- Cortex: Contains B-cell follicles (primary and secondary).
- Paracortex: Rich in T-cells; poorly developed in DiGeorge syndrome.
- Medulla: Contains medullary cords (plasma cells) and sinuses (macrophages).
Function: Filters lymph, traps antigens, and provides a site for lymphocyte activation and proliferation.

Lymph Node Anatomy and Tissue Components

⭐ Virchow's Node: The left supraclavicular node (Virchow's node) is a classic site of metastasis for abdominal malignancies, particularly gastric cancer.

Head & Neck Drainage - The Cervical Chains

Cervical Lymph Node Levels and Regions

Superficial Cervical Nodes: Follow the external jugular vein; drain superficial structures.
Deep Cervical Nodes (DCN): Along the internal jugular vein; the final common pathway for all head/neck lymph.
- Jugulodigastric Node: Drains tonsils & pharynx.
- Jugulo-omohyoid Node: Drains the tongue.

⭐ Virchow's Node (Left Supraclavicular): Part of the DCN, receives drainage from the thoracic duct. Its enlargement (Troisier's sign) strongly suggests metastatic abdominal malignancy (e.g., gastric cancer).

Torso & Viscera Drainage - The Central Hubs

Most lymph from below the diaphragm, the left side of the thorax, head, neck, and left arm drains via the Thoracic Duct, which begins at the Cisterna Chyli (~L1/L2).

Thoracic Duct and Cisterna Chyli Anatomy

Key Pre-Aortic Nodes:
- Celiac: Drains stomach, liver, spleen, pancreas, upper duodenum.
- Superior Mesenteric (SMA): Drains lower duodenum, jejunum, ileum, colon to splenic flexure.
- Inferior Mesenteric (IMA): Drains colon from splenic flexure to upper rectum.

⭐ Virchow's Node: The left supraclavicular node. As the terminus of the thoracic duct, its enlargement (Troisier's sign) can signal metastasis from abdominal malignancies (e.g., gastric cancer).

Limbs & Pelvis Drainage - The Peripheral Network

Upper Limb: Most lymphatics follow veins to axillary nodes.
- Medial hand/forearm → epitrochlear nodes → axillary nodes.
- Lateral arm/forearm → deltopectoral nodes → axillary nodes.
Lower Limb:
- Medial foot/leg → superficial inguinal nodes (follows great saphenous vein).
- Lateral foot/posterior leg → popliteal nodes → deep inguinal nodes.
Pelvis & Perineum:
- Pelvic organs → iliac & sacral nodes.
- Anal canal (below pectinate line), scrotum, vulva → superficial inguinal nodes.

⭐ Testicular cancer metastasizes to para-aortic nodes, while scrotal cancer spreads to superficial inguinal nodes.

Female Pelvic Lymphatic Drainage

High‑Yield Points - ⚡ Biggest Takeaways

Lymph nodes are a primary site for antigen presentation and a common pathway for cancer metastasis.

Left supraclavicular (Virchow's) node enlargement is a classic sign of abdominal malignancy (e.g., gastric cancer).

Axillary lymph node status is the most important prognostic factor in breast cancer.

Superficial inguinal nodes drain the lower limb, external genitalia, and perineum.

Painless, firm, and fixed lymph nodes are highly suspicious for malignancy.

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