J Med Cases

Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Med Cases and Elmer Press Inc

Journal website https://jmc.elmerpub.com

Case Report

Volume 17, Number 9, September 2026, pages 439-448

Microscopic Polyangiitis With Pituitary Dysfunction and Spontaneous Renal Aneurysm Rupture

↓ Figure 1. Magnetic resonance imaging (MRI), computed tomography (CT), and arterial angiography images of the patient. (a) Sagittal and coronal pituitary T1-weighted MRI showing local signal enhancement (yellow arrow). (b) Sagittal and coronal pituitary T1-weighted MRI showing normal signal (yellow arrow). (c) Abdominal CT scan showing a large right-sided perinephric and intracapsular hematoma in the right kidney (yellow arrow). (d) Arterial angiography showing active bleeding from the superior segmental and interlobular renal artery of the right kidney. Disseminated arterial microaneurysms are indicated by a yellow arrow (upper panel). Highly selective arterial embolization of the interlobular artery of the right kidney using microcoils (lower panel).

↓ Figure 2. Treatment strategies of this patient. (a) White blood cell (WBC), hemoglobin (HGB), and red blood cell (RBC) response in relation to the serial treatment. (b) Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels in the serial treatment.

↓ **Table 1.** Reported Cases of Pituitary Dysfunction in Patients With MPA
Items	Li/2020 [6]	Funauchi/2002 [7]	Mercedes/2025 [8]	This case
ANCA: antineutrophil cytoplasmic antibody; CTX: cyclophosphamide; F: female; HD-GC: high dose glucocorticoid; M: male; MPA: microscopic polyangiitis; MPO: myeloperoxidase; MRI: magnetic resonance imaging; PD-GC: pulse dose glucocorticoid; PET-CT: positron emission tomography-computed tomography.
Sex/age	M/61	F/62	F/41	F/59
Auto-antibody	MPO-ANCA	MPO-ANCA	MPO-ANCA	MPO-ANCA
Onset of pituitary injury	Onset of MPA	2 months before MPA diagnose	2 weeks before MPA diagnose	Onset of MPA
Symptoms of Pituitary injury	Polydipsia, polyuria, and erectile dysfunction	Polydipsia, polyuria	Persisted headache, sinus/facial discomfort	Polydipsia, polyuria
Imaging findings	MRI (negative), PET-CT: increased linear radioactivity uptake in pituitary fossa	MRI: swelling of the pituitary gland and loss of the high intensity signal of posterior lobe	MRI: enlarged heterogeneous pituitary gland with infundibular thickening	MRI: enlargement of pituitary gland and local signal enhancement
Treatment	PD-GC and HD-GC + CTX	Prednisolone for 4 weeks	GC and rituximab	PD-GC and HD-GC+CTX
Hormone replacement	Desmopressin	Desmopressin	None	Desmopressin
Outcomes	Partial remission	Remission	Remission	Remission

↓ Table 1. Reported Cases of Pituitary Dysfunction in Patients With MPA

Items

Li/2020 [6]

Funauchi/2002 [7]

Mercedes/2025 [8]

This case

ANCA: antineutrophil cytoplasmic antibody; CTX: cyclophosphamide; F: female; HD-GC: high dose glucocorticoid; M: male; MPA: microscopic polyangiitis; MPO: myeloperoxidase; MRI: magnetic resonance imaging; PD-GC: pulse dose glucocorticoid; PET-CT: positron emission tomography-computed tomography.

Sex/age

M/61

F/62

F/41

F/59

Auto-antibody

MPO-ANCA

Onset of pituitary injury

Onset of MPA

2 months before MPA diagnose

2 weeks before MPA diagnose

Onset of MPA

Symptoms of Pituitary injury

Polydipsia, polyuria, and erectile dysfunction

Polydipsia, polyuria

Persisted headache, sinus/facial discomfort

Polydipsia, polyuria

Imaging findings

MRI (negative), PET-CT: increased linear radioactivity uptake in pituitary fossa

MRI: swelling of the pituitary gland and loss of the high intensity signal of posterior lobe

MRI: enlarged heterogeneous pituitary gland with infundibular thickening

MRI: enlargement of pituitary gland and local signal enhancement

Treatment

PD-GC and HD-GC + CTX

Prednisolone for 4 weeks

GC and rituximab

PD-GC and HD-GC+CTX

Hormone replacement

Desmopressin

None

Desmopressin

Outcomes

Partial remission

Remission

↓ **Table 2.** Reported Cases of Renal Aneurysm in Patients With MPA
Case/year	Sex/age	Auto-antibody	Presentation	Imaging examinations	Involved artery	Perirenal hematomas	Treatment	Outcomes
ANCA: antineutrophil cytoplasmic antibody; CT: computed tomography; CTA: computed tomography angiography; CTX: cyclophosphamide; F: female; HD: hemodialysis; IV MP: intravenous methylprednisolone; M: male; MPO: myeloperoxidase; NA: not available; PE: plasm exchange.
Inatsu/2002 [14]	M/78	MPO-ANCA	Slight fever and weight loss, RPGN	Arterial angiography	Bilateral renal artery	No	Steroids	Recovered, HD
Tamei/2008 [11]	M/55	MPO-ANCA	Sharp pain on the left side, shock	Abdominal CT and arterial angiography	Left renal, hepatic artery	Yes, left	Blood transfusion, steroids	Recovered, HD
Dhaun/2013 [15]	M/56	MPO-ANCA	Bilateral loin pain	CT and CTA	Bilateral renal, hepatic, mesenteric artery	Yes, bilateral	Steroids + CTX, PE	Recovered
Jira/2013 [16]	M/56	MPO-ANCA	Severe right iliac fossa pain hemodynamic shock	Renal arteriography	Bilateral renal artery	Yes, right	IV MP + CYC, oral steroids	Recovered
Nakashima/2015 [24]	F/77	MPO-ANCA	RPGN, both flank pain	Abdominal CT and ultrasonography	Bilateral renal artery	Yes, bilateral	Oral steroids	Recovered, HD
Ishiwatari/2018 [10]	F/82	MPO-ANCA	RPGN, decreased urinary volume, decreased hemoglobin	Abdominal CT	Right renal artery	Yes, right	Coil embolization, IV MP, oral steroids mizoribine	Recovered, HD
Yu/2018 [17]	M/61	MPO-ANCA	Left lumbago, decreased hemoglobin	Contrast enhanced CT	Bilateral renal, hepatic, and mesenteric artery	Yes, left	Nephrectomy in emergency	NA
Zhang/2019 [18]	F/57	MPO-ANCA	Severe lumbago, acute renal failure, and hemorrhagic shock	Abdominal CT	Bilateral renal artery	Yes, bilateral	IV MP, oral steroids	Recovered
Andrew/2020 [19]	F/50	MPO-ANCA	Abdominal pain, decreased hemoglobin	Abdominal CT, contrast enhanced CT	Bilateral renal, hepatic artery	Yes, bilateral	Percutaneous drainage of hematoma, IV MP and CYC	NA
Nunes/2022 [20]	M/52	Negative (kidney biopsy)	Severe abdominal pain and hemorrhagic shock	CTA	Left renal artery	Yes, left	Coil embolization, IV MP + CYC, oral steroids	Recovered
Zhao/2023 [21]	F/56	MPO-ANCA	Back pain	Abdominal CT	Right renal artery	Yes, right	Oral steroids + CTX, PE	Recovered
Tang/2024 [22]	M/61	MPO-ANCA	Low back pain, decreased hemoglobin	Renal ultrasonography, arteriography	Bilateral renal artery	Yes, bilateral	IV MP + CYC, PE and coil embolization	Recovered, HD
Jana/2025 [23]	F/45	MPO-ANCA	Severe abdominal pain, drop in hemoglobin	Abdominal CT, MRI, and CTA	Left renal artery	Yes, left	IV MP + CYC, oral steroids	Recovered
This case	F/59	MPO-ANCA	Sharp pain in her right waist area, hypotension, decreased hemoglobin	Abdominal CT, contrast enhanced CT, arteriography	Right renal artery	Yes, right	Coil embolization, IV MP + CYC, oral steroids	Recovered

↓ Table 2. Reported Cases of Renal Aneurysm in Patients With MPA

Case/year

Sex/age

Auto-antibody

Presentation

Imaging examinations

Involved artery

Perirenal hematomas

Treatment

Outcomes

ANCA: antineutrophil cytoplasmic antibody; CT: computed tomography; CTA: computed tomography angiography; CTX: cyclophosphamide; F: female; HD: hemodialysis; IV MP: intravenous methylprednisolone; M: male; MPO: myeloperoxidase; NA: not available; PE: plasm exchange.

Inatsu/2002 [14]

M/78

MPO-ANCA

Slight fever and weight loss, RPGN

Arterial angiography

Bilateral renal artery

Steroids

Recovered, HD

Tamei/2008 [11]

M/55

MPO-ANCA

Sharp pain on the left side, shock

Abdominal CT and arterial angiography

Left renal, hepatic artery

Yes, left

Blood transfusion, steroids

Recovered, HD

Dhaun/2013 [15]

M/56

MPO-ANCA

Bilateral loin pain

CT and CTA

Bilateral renal, hepatic, mesenteric artery

Yes, bilateral

Steroids + CTX, PE

Recovered

Jira/2013 [16]

M/56

MPO-ANCA

Severe right iliac fossa pain hemodynamic shock

Renal arteriography

Bilateral renal artery

Yes, right

IV MP + CYC, oral steroids

Recovered

Nakashima/2015 [24]

F/77

MPO-ANCA

RPGN, both flank pain

Abdominal CT and ultrasonography

Bilateral renal artery

Yes, bilateral

Oral steroids

Recovered, HD

Ishiwatari/2018 [10]

F/82

MPO-ANCA

RPGN, decreased urinary volume, decreased hemoglobin

Abdominal CT

Right renal artery

Yes, right

Coil embolization, IV MP, oral steroids mizoribine

Recovered, HD

Yu/2018 [17]

M/61

MPO-ANCA

Left lumbago, decreased hemoglobin

Contrast enhanced CT

Bilateral renal, hepatic, and mesenteric artery

Yes, left

Nephrectomy in emergency

Zhang/2019 [18]

F/57

MPO-ANCA

Severe lumbago, acute renal failure, and hemorrhagic shock

Abdominal CT

Bilateral renal artery

Yes, bilateral

IV MP, oral steroids

Recovered

Andrew/2020 [19]

F/50

MPO-ANCA

Abdominal pain, decreased hemoglobin

Abdominal CT, contrast enhanced CT

Bilateral renal, hepatic artery

Yes, bilateral

Percutaneous drainage of hematoma, IV MP and CYC

Nunes/2022 [20]

M/52

Negative (kidney biopsy)

Severe abdominal pain and hemorrhagic shock

CTA

Left renal artery

Yes, left

Coil embolization, IV MP + CYC, oral steroids

Recovered

Zhao/2023 [21]

F/56

MPO-ANCA

Back pain

Abdominal CT

Right renal artery

Yes, right

Oral steroids + CTX, PE

Recovered

Tang/2024 [22]

M/61

MPO-ANCA

Low back pain, decreased hemoglobin

Renal ultrasonography, arteriography

Bilateral renal artery

Yes, bilateral

IV MP + CYC, PE and coil embolization

Recovered, HD

Jana/2025 [23]

F/45

MPO-ANCA

Severe abdominal pain, drop in hemoglobin

Abdominal CT, MRI, and CTA

Left renal artery

Yes, left

IV MP + CYC, oral steroids

Recovered

This case

F/59

MPO-ANCA

Sharp pain in her right waist area, hypotension, decreased hemoglobin

Abdominal CT, contrast enhanced CT, arteriography

Right renal artery

Yes, right

Coil embolization, IV MP + CYC, oral steroids

Recovered