Primary hypertrophic osteoarthropathy: genetics, clinical features and management

Insights into Natural History, Phenotypic, and Molecular Spectrum in a Large Cohort of Osteosclerotic Disorders

Osteosclerotic bone diseases include more than 30 rare diseases characterized by excessive bone formation. The aim of this study is to compare the molecular pathogenesis and prognostic features of 12 different osteosclerotic diseases. Thirty-four patients from 23 families were included, 25 of whom were followed for a period of one to 22 years. Exome sequencing was performed in 20 families. Primary hypertrophic osteoarthropathy (PHOAR1/2) was found in 12 patients, followed by juvenile Paget's disease (JPD)-5 in five, craniometaphyseal dysplasia (CMD) and Camurati-Engelmann disease (CED) in four, Ghosal hematodiaphyseal dysplasia (GHDD) in three patients, sclerosteosis-1 in two patients, and ultra-rare diseases including trichothiodystrophy-1, prenatal Caffey disease, melorheosteosis, and Lenz-Majewski hyperostotic dwarfism in one patient each. Patients with CMD and sclerosteosis-1 had severe cranial sclerosis leading to facial dysmorphism. CMD was characterized by metaphyseal widening, radiolucency, and diaphyseal sclerosis of the long bones in early childhood and later developed Erlenmeyer flask deformity sparing the vertebrae and pelvis, whereas sclerosteosis-1 manifested as generalized sclerosis. CED and GHDD share bone pain, difficulty in walking, and diaphyseal sclerosis, with some patients also having bone marrow involvement. Interestingly, patients with CED and JPD-5 showed osteopenia in early childhood, followed by the development of osteosclerosis in late childhood. Clinical and radiologic findings improved over time in PHOAR1 patients, whereas they progressed in JPD-5 and trichothiodystrophy-1 patients. Intra- and interfamilial clinical differences were observed in CMD, CED, JPD-5, and GHDD. The knowledge gained about the natural history of osteosclerotic diseases will make an important contribution to their diagnosis and management.

Nail Clubbing: A Dermatologic Window into Underlying Systemic Disease - an All of Us Study

Introduction

Nail clubbing is defined as distal phalanx thickening resulting in a bulbous appearance of the digit. We aimed to describe non-pulmonary medical conditions associated with nail clubbing using a cross-sectional approach.

Methods

We conducted a cross-sectional analysis of the All of Us Research Program, identifying nail clubbing patients by ICD-10-CM and/or SNOMED code. Nail clubbing patients with pulmonary disease (cases) were compared to nail clubbing patients without pulmonary disease (controls). Fisher's exact test/Pearson's χ2 test analyzed categorical variables. Independent two-sample t tests analyzed continuous variables. Odds ratios (ORs) were analyzed with multivariate logistic regression adjusted for sociodemographic characteristics.

Results

In total, 85 participants had nail clubbing, of which 63.53% had a pulmonary disease versus 36.47% of controls. Overall, across both cases and controls, 22% of patients had chronic liver disease, 17% hypothyroidism, 8% HIV infection, and 5% Graves' disease/hyperthyroidism. Male versus female patients with nail clubbing had decreased odds of having concurrent respiratory disease diagnosis (OR, 0.37; 95% CI, 0.14-0.92, p = 0.03).

Conclusion

Greater than one-third of patients had nail clubbing associated with a non-pulmonary systemic disease, and a significant proportion were male. Consideration of a broad differential of pathologies associated with nail clubbing is needed to initiate workup and make appropriate screening referrals.

Primary hypertrophic osteoarthropathy: phenotypic variability and penetrance rate in heterozygotes for SLCO2A1 variants

Primary hypertrophic osteoarthropathy (PHO) is a rare autosomal recessive disease caused by pathogenic variants (PVs) in HPGD and SLCO2A1 genes whose phenotypes are, respectively, designated as PHOAR1 and PHOAR2. Recently, a dominant inherited form (PHOAD) was identified in SLCO2A1 heterozygotes whose PHO penetrance is widely unknown, and data on phenotype are markedly limited. Our aim was to reveal the penetrance and extend/refine data on phenotype of SLCO2A1 heterozygotes. Both genes were sequenced using Sanger sequencing. The 4 probands had a typical complete form (CF) of PHO. Mean ages at symptom onset and clinical diagnosis were, respectively, 18.5 ± 2.7 (16-22) years and 22 ± 3.4 (18-26) years. They were homozygotes for SLCO2A1 (p.Q188R, p.C420F, p.A176T; p.G104*) PVs; 2 were novel variants. We focused on 14 SLCO2A1 heterozygous screened relatives from 3 families: 5 elderly individuals (mean age: 78 ± 6.7 [72-86] years) of the parental generation were affected, 2 by incomplete form (IF) and 3 with isolated digital clubbing (IDC). Combining our 14 carriers and 33 reported so far, the estimated overall PHO penetrance was 70%, being significantly higher in men (83% vs 50%; p = .024) and individuals carrying truncated SLCO2A1 PVs (88% vs 53%; p = .053). In turn, the periostosis penetrance rate in women was 28% (5/18), including our oldest patient (86 years). In the probands, the predominant phenotypes were CF (64%) and IF (36%). Among screened carriers, phenotypes were IDC (41%) followed by IF and fruste form (FF) (28%, each), whereas IDC and FF were the predominant phenotypes in screened men and women, respectively. As a novelty, we uncovered an incomplete penetrance of PHO in SLCO2A1 heterozygotes, with higher rates in elderly individuals, males, and those with truncated PVs. Regarding phenotype, PHO is more pronounced in males, periostosis is likely more frequent in females than previously documented in PHOAR2, and IDC may represent a distinct clinical feature in SLCO2A1 heterozygotes.

Single-cell characterization of the human C2 dorsal root ganglion recovered from C1-2 arthrodesis surgery: implications for neck pain

Neurons in the dorsal root ganglion (DRG) receive and transmit sensory information from the tissues they innervate and from the external environment. Upper cervical (C1-C2) DRGs are functionally unique as they receive input from the neck, head, and occipital cranial dura, the latter two of which are also innervated by the trigeminal ganglion (TG). The C2 DRG also plays an important role in neck pain, a common and disabling disorder that is poorly understood. Advanced transcriptomic approaches have significantly improved our ability to characterize RNA expression patterns at single-cell resolution in the DRG and TG, but no previous studies have characterized the C2 DRG. Our aim was to use single-nucleus and spatial transcriptomic approaches to create a molecular map of C2 DRGs from patients undergoing arthrodesis surgery with ganglionectomy. Patients with acute (<3 months) or chronic (≥3 months) neck pain were enrolled and completed patient-reported outcomes and quantitative sensory testing prior to surgery. C2 DRGs were characterized with bulk, single nucleus, and spatial RNA sequencing technologies from 22 patients. Through a comparative analysis to published datasets of the lumbar DRG and TG, neuronal clusters identified in both TG and DRG were identified in the C2 DRG. Therefore, our study definitively characterizes the molecular composition of human C2 neurons and establishes their similarity with unique characteristics of subsets of TG neurons. We identified differentially expressed genes in endothelial, fibroblast and myelinating Schwann cells associated with chronic pain, including FGFBP2, C8orf34 and EFNA1 which have been identified in previous genome and transcriptome wide association studies (GWAS/TWAS). Our work establishes an atlas of the human C2 DRG and identifies altered gene expression patterns associated with chronic neck pain. This work establishes a foundation for the exploration of painful disorders in humans affecting the cervical spine.

History of primary hypertrophic osteoarthropathy

Primary hypertrophic osteoarthropathy (PHO) is a rare systemic disorder characterized. by periosteal new bone formation, clubbing of fingers and toes, and thickening of the. skin, particularly on the forehead and face. This case study presents a 24-year-old. male patient with a decade-long history of prominent skin folds on the forehead and. face, joint swelling in hands and feet, and calf pain. Clinical manifestations included. progressive facial wrinkling, thickening of distal joints, and cortical thickening observed. on X-rays. Serum levels of insulin-like growth factor (IGF-1), thyroid function, rheumatoid factor, and anti-cyclic citrullinated peptide were within normal ranges. The diagnosis was confirmed through a comprehensive evaluation of clinical, radiological, and laboratory findings. This report underscores the importance of recognizing the. distinct features of PHO for accurate diagnosis and timely management.

Two cases of primary hypertrophic osteoarthropathy caused by HPGD variants: a case report and literature review

BACKGROUND

Primary hypertrophic osteoarthropathy (PHO) is a rare genetic disorder primarily characterized by digital clubbing, pachydermia, and periostitis. The rarity of this disease often leads to misdiagnosis or delayed diagnosis.

METHODS

We describe the clinical and genetic findings of two pediatric PHO cases caused by HPGD variants and perform a systematic literature review of HPGD-related PHO cases.

RESULTS

Both patients exhibited congenital digital clubbing and patent ductus arteriosus from birth. Radiographs revealed cortical bone thickening and a periosteal reaction. Patient 1 displayed gait abnormalities and delayed cranial suture closure, while Patient 2 had bilateral leg swelling. Whole exome sequencing identified a compound heterozygous variant (NM_000860.6: c.189C > A, p.C63* and NM_000860.6: c.310_311delCT, p. L104Afs*3) in Patient 1 and a homozygous splice-site variant (NG_011689.1(NM_000860.6): c.324 + 5G > A) in Patient 2. All variants were classified as pathogenic based on the American College of Medical Genetics and Genomics criteria. Among 89 reviewed cases, the c.310_311delCT variant accounted for 37.1% (33/89), predominantly in homozygous form (60.6%, 20/33). The median urinary prostaglandin E2 (PGE2)-to-creatinine ratio in PHO patients was 627.1 ng/mmol (normal: 61.49 ng/mmol). Notably, the median age of symptom onset was 5.1 years, while diagnosis occurred at 22.1 years, with a male predominance (male-to-female ratio: 2.2:1).

CONCLUSION

We report the first HPGD c.189C > A variant, expanding the genetic spectrum of PHO. The c.310_311delCT variant represents a recurrent hotspot, predominantly in homozygosity. Our findings highlight the importance of early genetic testing and multidisciplinary management to reduce diagnostic delays and improve outcomes.

Generalized sarcoidosis associated with hypertrophic osteopathy in a Standardbred racehorse

A Standardbred racehorse was presented for exercise intolerance, weight loss, pyrexia and facial deformity. Radiography and ultrasonography revealed periostitis and regional soft tissue swelling of maxillary bones. Computed tomography excluded any dental or sinus origin of these abnormalities. Further deformities on distal limbs and skin lesions appeared during hospitalization. Radiography identified bilateral periostitis and soft tissue swelling in the distal radius and metatarsal bones, as observed in the head, suggestive of hypertrophic osteopathy (HO). Skin biopsies revealed granulomatous dermatitis, indicating equine sarcoidosis (ES). The horse was euthanized due to rapid deterioration of his condition. Post-mortem examination and histopathology revealed splenomegaly, several pulmonary nodules and disseminated granulomatous lesions. These findings confirmed the diagnosis of generalized ES, or equine idiopathic systemic granulomatous disease. The concurrent with HO was probably associated with the intrathoracic pathology. Polymerase chain reaction (PCR) on pooled tissues identified equine herpesvirus 5 (EHV-5) DNA.

Pachydermoperiostosis Due to a Novel HPGD Splicing Site Mutation Masquerading as Acromegaly

Hypertrophic osteoarthropathy (HOA: MIM 167100)) is classified into primary and secondary types. Primary HOA, also known as pachydermoperiostosis (PDP), is a rare genetic condition with distinct clinical features including digital clubbing, skin thickening, and periostosis. Secondary HOA often occurs as a paraneoplastic syndrome or is associated with systemic diseases. In this report, we present a 17-year-old male patient who initially presented with significant digital clubbing, enlarged hands and feet, and excessive sweating. Although the initial suspected diagnosis was acromegaly, the patient's plasma level of insulin-like growth factor 1 was normal and growth hormone levels suppressed to <1 ng/dL following oral glucose tolerance test. Whole exome sequencing followed by Sanger sequencing of leukocyte deoxyribonucleic acid revealed a novel splicing variant in the 15-hydroxyprostaglandin dehydrogenase (HPGD) gene (NM_000860.6: c.662 + 5_662 + 8del). Reverse transcription polymerase chain reaction confirmed that this variant led to defective splicing with skipping of exon 6, a frameshift, and truncation at codon 13 of exon 7 downstream. His symptoms did not respond well to nonsteroidal anti-inflammatory drugs but showed excellent response to a trial of lanreotide autogel that has been used for about 1 year.

Targeting Metabolomics in Primary Hypertrophic Osteoarthropathy: Uncovering Novel Insights into Disease Pathogenesis

CONTEXT

Primary hypertrophic osteoarthropathy (PHO) is a rare genetic disorder characterized by skeletal and skin abnormalities. Genetic defects in prostaglandin E2 (PGE2) metabolism are known to cause PHO. However, the global impact and clinical significance of eicosanoids and oxylipins beyond PGE2 remain to be elucidated.

OBJECTIVE

This study aimed to investigate oxylipin networks in PHO, including the 2 subtypes, PHOAR1 and PHOAR2, and examine their associations with clinical characteristics.

METHODS

We conducted a targeted metabolomic study involving 16 patients with PHO and 16 age- and sex-matched healthy controls. Serum samples were collected at the time of diagnosis. Metabolites were quantified using ultra-high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

Laboratory analyses confirmed elevated levels of PGE2 in patients with PHO, consistent with the established pathogenesis. About 60 oxidized lipid metabolites were identified, with 19 differentially expressed in PHO. Besides the COX/PGE2 pathway, the lipoxygenase-mediated pathway was also involved in PHO. The metabolites 5-OxoETE, 15-OxoETE, 8S,15S-DiHETE, PGE2, 11β-PGE2, PGB2, LTB4, and LTE4 were significantly altered. Correlation analyses revealed associations between oxylipin metabolites and clinical features, including bone microarchitecture. Notably, the study highlighted differences in the oxylipin metabolite profiles between patients with PHOAR1 and patients with PHOAR2, suggesting distinct metabolic signatures for each subtype.

CONCLUSION

Our study indicated a significant perturbation in oxylipin metabolism among patients with PHO, with distinct metabolic signatures observed between PHOAR1 and PHOAR2. The disruption extended beyond the metabolism of PGE2. It encompassed a broader alteration across the polyunsaturated fatty acid metabolism spectrum, including various eicosanoids and oxylipins. Our work provided a comprehensive understanding of the pathogenesis of PHO, and underscored the potential for subtype-specific therapeutic interventions.

Digital clubbing without hypoxia for lysinuric protein intolerance

Digital clubbing is characterized by bulbous enlargement of the terminal segments of the fingers. Hypotheses including hypoxia have been proposed for the pathogenesis of digital clubbing, but the exact pathogenesis of digital clubbing is still uncertain. Lysinuric protein intolerance (LPI) is caused by pathogenic variants in SLC7A7 and is often associated with interstitial lung disease. Previously two patients of LPI with digital clubbing but without hypoxia have been reported. It is unclear whether digital clubbing in LPI is secondary to hypoxia or directly related to SLC7A7 deficiency. Here we report a 6-year-old Japanese boy presented with digital clubbing without hypoxia. He had episodic vomiting, each episode consisting of a single vomiting event occurring once a month, and his growth had been delayed. He had interstitial lung disease and hepatomegaly. He had compound heterozygous pathogenic variants in the SLC7A7, leading to the diagnosis of LPI. Together with the two previously reported patients mentioned above, we conclude that digital clubbing can occur in the absence of hypoxia. Digital clubbing in the absence of hypoxia has been observed in two genetic disorders related to prostaglandin (PG) E2, HPGD and SLCO2A1. PGE2 synthesis is primarily regulated by the cyclooxygenase 2, which plays a critical role in the control of inflammation. A high urine PGE level in the patient was compatible with the notion that PGE2 production may be increased in LPI. The occurrence of digital clubbing in the absence of hypoxia in LPI patients with SLC7A7 may be attributed to the mechanism of increased PGE2 production.

Clinical Outcomes of Utilizing a "W"-shaped Incision in the Management of Forehead Skin Thickening Induced by Hypertrophic Osteoarthropathy

BACKGROUND

Hypertrophic osteoarthropathy (HOA) is a rare and intricate hereditary disease. The appearance and functional deformity of the forehead caused by thickened folds are the main clinical manifestations of patients with hypertrophic osteoarthropathy. The cause of this disease is still unknown. Currently, surgical treatment has become one of the best strategies, mainly for improving the appearance of the forehead. There has been no literature report on the use of "W"-shaped skin flap resection for thickened forehead skin in patients with hypertrophic osteoarthropathy.

METHODS

All cases of hypertrophic osteoarthropathy in our department in the last 7 years, and previous literature on hypertrophic osteoarthropathy, were reviewed.

RESULTS

A total of 5 cases of hypertrophic osteoarthropathy in our department (mean age 21 years, all male patients) were reviewed. All patients underwent open surgery to remove the thickened skin on the forehead or the wrinkles and gyrus-shaped scalp. The jagged skin tissue was removed (8-9) cm × (1-2.5) cm × 0.5 cm. The folds and thickness of the frontal skin of the patients were greatly improved after the operation. Patient satisfaction with the treatment outcomes was unanimous. However, one case experienced a postoperative wound infection during follow-up. The utilization of the "W"-shaped excision technique allowed for the maximal removal of excessively diseased tissue, thereby facilitating a smoother resolution of the depression.

CONCLUSIONS

A total of 5 cases of hypertrophic osteoarthropathy were treated in our department, and all of them underwent frontal skin "W"-shaped excision, which was safe, feasible, and practical, and the postoperative results were satisfactory.

LEVEL OF EVIDENCE IV

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Comprehensive Treatment of a Rare Case of Complete Primary Pachydermoperiostosis with Large Facial Keloid Scars: A Case Report and Literature Review

Introduction

Pachydermoperiostosis (PDP), or primary hypertrophic osteoarthropathy, is a rare autosomal dominant disease with primary clinical features of pachydermia (thickening of skin) and periostosis (new bone formation). Keloid scar formation is also rather obscure, and some scientists have claimed that keloid scars contain an excessive amount of fibroblasts compared with normal skin as well as a dense mass of irregularly deposited connective tissues.

Case Presentation

A 25-year-old man exhibited extensive skin folding on his face, a gyrus-like scalp, depressed nasolabial folds, and keloids. Symptoms began at 18 years of age, progressing insidiously. Additionally, he experienced clubbing of fingers and toes, joint pain, muscle soreness, and hyperhidrosis. Radiographic examinations revealed thickened bone and cystic regions. Diagnosed with complete primary PDP and facial keloid scars, he underwent skin dermabrasion, biopsies, and a comprehensive treatment involving, botulinum toxin injections, 5-fluorouracil, and a carbon dioxide lattice laser.

Conclusion

PDP presents challenges due to its unclear etiology but stabilizes over time in most cases. Comprehensive treatment strategies, including dermabrasion and a combination of intralesional therapies, are effective in managing keloids in PDP patients. This case contributes to the understanding of managing rare diseases and underscores the importance of personalized approaches to improve therapeutic outcomes in patients with complete primary PDP and concurrent keloids.