Primary hypertrophic osteoarthropathy: genetics, clinical features and management

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.

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.

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

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.