Case challenge| 64-year-old man, what is the cause of back pain after modified radical mastectomy for breast cancer?

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General

Patient, male, 64 years old, working as an electrician
.

Complaints: The patient feels pain
in the lower right side of the back.

Present medical history: the patient complained of a right breast mass for 4 months 7 years ago, and after hollow core needle biopsy, the pathology showed estrogen receptor (ER) positive and HER2-negative breast cancer
.
Modified radical resection of right breast cancer, pathological stage IIA
.
Adjuvant tamoxifen was used for 5 years
after surgery.
Two years after treatment, the patient reported pain
in the lower right side of the back.

Past medical and drug history: previous health
.
Patients have a history of alcohol consumption (up to 1-2 drinks 2 to 3 times per week).

Family history: Denial of family history
of breast or other cancers.

physical examination

Vital signs: temperature: normal; Pulse: 74 beats/min; Blood pressure: 138/87mmHg; Oxygen saturation: 98%.

General examination: the patient has a clear expression and answers correctly
.
The oral mucosa is moist and normal
.
The respiratory movement of both lungs in the chest is consistent, and the breath sounds of both lungs are clear on auscultation, and there are no dry and wet rales
.
The heart rhythm is aligned, and no murmurs and other abnormal heart sounds
are heard.
The abdomen is flat, non-tender, and the liver and spleen are not palpable
.
Both upper and lower limbs have normal muscle strength and free movement
.

Ancillary examination

Blood routine and biochemical tests: no abnormalities
.

Imaging tests:

MRI of the pelvis showed complex osteolytic changes in the right iliac wing, with lesion sizes of 5.
5 × 2.
6 × 3 .
6cm
.

PET/CT showed a heterogeneous mass in the lower right lobe of the liver, with a maximum standardized uptake value (SUV) of 7.
1, a maximum SUV value of 8.
8 for anterior hepatic lesions, and a maximum SUV value of 5.
6
for right iliac anterior wing lesions.

diagnosis

Current diagnosis:

Postoperative metastasis of breast cancer

Metastasis of bone (right iliacium).

Liver metastases

Diagnosis basis: liver and bone tissue biopsy pathology is the gold standard
for diagnosis.

discuss

1.
Characteristics of the disease

Male breast cancer is rare, accounting for less than 1%
of all breast cancer cases.
The American Cancer Society estimates 2,710 new cases of invasive breast cancer in the United States in 2022 and 287,850 in women ^[2].

Because male breast cancer is rare, most disease information is obtained from single-center retrospective studies and extrapolated from clinical practice in female breast cancer
.

Studies have shown that the following risk factors are associated with male breast cancer:

Genetic predisposition: a major risk factor
for breast cancer in men.
About 15% to 20% of men with breast cancer have a family history
of breast or ovarian cancer.
BRCA2 mutations account for approximately 15 percent of all breast cancers in men, and men with BRCA2 mutations have a lifetime risk (LR) of 5 to 10 percent, compared with 0.
1 percent in the general population [3].

In addition, BRCA1 mutations are associated with male breast cancer less than BRCA2, with an LR of about 1% to 5%.

Other gene mutations, including PTEN, p53 and CHEK2, have been linked
to the development of male breast cancer.

Klinefelter syndrome: also known as XXY syndrome or Kirschner syndrome, it is characterized by 47,XXY karyotype, small testicles, azoospermia, and dysplasia
of secondary sexual characteristics.
Klinefelter syndrome increases the risk of breast cancer in men by more than
50 times.
About 4%-20% of male breast cancer patients have Klinefelter syndrome
.

Other: cryptorchidism, congenital inguinal hernia, orchiectomy, orchitis, testicular injury, and infertility
.
Lifestyle risk factors include obesity and alcohol
abuse.

Male breast cancer often presents with painless breast lumps, pain, inverted nipples, and nipple discharge
.
Differential diagnoses include breast development, infection, lipoma, fibroid, granuloscytoma, or single metastases
of rare primary tumors.

Due to poor understanding of male breast cancer, male breast cancer is generally staged later than female at presentation, and the prognosis is relatively poor
.
The Male Breast Cancer Database suggests that from 2005 to 2010, the 5-year survival rate for male breast cancer was 82.
8%, compared with 88.
5%
for female breast cancer.
In addition, men have a 43% higher risk of dying from breast cancer than women
.

Examination for suspicious lumps in the male breast is similar to that of women, with mammary molybdenum and palladium being
preferred.
Previous studies have shown that the sensitivity and specificity of mammary molybdenum palladium examination for the diagnosis of malignant breast cancer in men is 92% and 90%,
respectively.

The main pathological classification of male breast cancer is invasive ductal carcinoma, which accounts for more than
80% of all cases.
The second most common subtype is ductal carcinoma
in situ.
Other less common subtypes include invasive papillary carcinoma and lobular carcinoma
.
Male breast cancer tends to have a higher rate of hormone receptor (HR) positivity compared to female breast cancer, with about 80% of male breast cancers being ER-positive and nearly 75% being progesterone receptor (PR) positive
.

The staging system for male breast cancer is the same as for women, with stages based on the size of the primary lesion, lymph node status, and the presence of distant metastatic disease
.
Prognostic factors for male breast cancer are also similar to female breast cancer, including axillary lymph node status, tumor size, histological grade, and HR status
.

2.
Treatment