Severe ulcerative proctitis, pyoderma gangrenosum, hidradenitis suppurativa and fever in a patient with a rare variant of the PSTPIP1 gene

Autoinflammatory syndromes are characterized by unprovoked, persistent inflammation. We describe a 67-year-old man who presented with severe proctitis, pyoderma gangrenosum, hidradenitis suppurativa and fever, and was found to have a rare variant of the PSTPIP1 gene. The patient had a history of Type 2 diabetes, hypertension and hypercholesterolaemia and was first investigated due to the presence of microscopic faecal blood at the age of 60 years. Adenomas were excised at this time. Four years later, the patient had an intestinal haemorrhage that led to anaemia. Colonoscopy detected ulcerations in the anal canal. The proctitis was self-limiting, but occasional bleeding prevailed. Three years later, palatal and scrotal ulcers were detected (Fig. 1a). The clinical and histological findings were suggestive of pyoderma gangrenosum (Fig. 2a). A week later, pustular lesions appeared on the patient’s buttocks, hips and shoulders (Fig. 1b), and histological analysis supported the diagnosis of hidradenitis suppurativa (Fig. 2b,c). Faecal calprotectin (FCP) level was 3825 μg/g faeces (positive at levels > 100 μg/g). The patient also had a fever of 38 °C. Colonoscopy revealed severe proctitis with deep ulcers (Fig. 1c). Computed tomography of the colon was normal.

Autoinflammatory syndromes are characterized by unprovoked, persistent inflammation. We describe a 67-year-old man who presented with severe proctitis, pyoderma gangrenosum, hidradenitis suppurativa and fever, and was found to have a rare variant of the PSTPIP1 gene.
The patient had a history of Type 2 diabetes, hypertension and hypercholesterolaemia and was first investigated due to the presence of microscopic faecal blood at the age of 60 years. Adenomas were excised at this time. Four years later, the patient had an intestinal haemorrhage that led to anaemia. Colonoscopy detected ulcerations in the anal canal. The proctitis was self-limiting, but occasional bleeding prevailed.
Three years later, palatal and scrotal ulcers were detected (Fig. 1a). The clinical and histological findings were suggestive of pyoderma gangrenosum (Fig. 2a).
A week later, pustular lesions appeared on the patient's buttocks, hips and shoulders (Fig. 1b), and histological analysis supported the diagnosis of hidradenitis suppurativa (Fig. 2b,c). Faecal calprotectin (FCP) level was 3825 µg/g faeces (positive at levels > 100 µg/g). The patient also had a fever of 38°C. Colonoscopy revealed severe proctitis with deep ulcers (Fig. 1c). Computed tomography of the colon was normal. The patient was treated with intravenous methylprednisolone 40 mg and 20 mg (morning and afternoon, respectively) for 5 days, followed by oral prednisolone, which was started at 40 mg and then tapered by 5 mg/week, with weekly subcutaneous injections of methotrexate 25 mg. After 7 weeks of treatment, the skin symptoms cleared. The intestinal bleeding also ceased, but the diarrhoea continued for several months. Magnetic resonance imaging showed proctitis. Prednisolone was continued at 10 mg/day, but methotrexate was stopped due to lymphopenia. Six months after starting the corticosteroids, sigmoidoscopy showed no inflammation, the FCP level had decreased and the patient was asymptomatic. The patient is currently taking methylprednisolone 5 mg/day and using topical mesalamine. Following informed consent from the patient, we performed genetic analyses on the patient's DNA extracted from peripheral blood. A targeted panel (Custom Clinical Exome Solution Kit; SOPHiA GENETICS SA, Saint Sulpice, Switzerland) was used for next-generation sequencing (Illumina, San Diego, CA, USA). Autoinflammatory syndrome-related gene sequences, including NCSTN, PSTPIP1, MEFV, NOD2 and NOD1, were screened. The assay provided 50 9 coverage of all target regions. Variant annotation and filtering were performed with DDM TM software (SOPHiA GENET-ICS SA) and visualized by the Integrative Genomics Viewer (https://software.broadinstitute.org/software/ igv/). The genetic analysis revealed a rare heterozygous variant [NM_003978.4, c.764C>T, p.(Thr255Met), rs766895096] in PSTPIP1. The variant had an allele frequency of 0.0072% in the gno-mAD database. The variant was localized to exon 11 and caused substitution of a moderately conserved threonine residue by a methionine at position 255. This substitution was likely to affect the secondary structure of the protein due to differences in the polarity, size and charge present with these residues. The variant had a Combined Annotation Dependent Depletion score of 22.5. The other tested genes were normal.
Several autoinflammatory syndromes are associated with a mutation in PSTPIP1, including PAPA (pyogenic sterile arthritis, pyoderma gangrenosum and acne), PASH (pyoderma gangrenosum, acne and suppurative hidradenitis), PAMI (PSTPIP1-associated myeloid-related-proteinaemia inflammatory), PAPASH (pyogenic arthritis, pyoderma gangrenosum, acne and suppurative hidradenitis), PAPA-like (pyogenic arthritis, pyoderma gangrenosum and acne-like) and PAC (pyoderma gangrenosum, acne and ulcerating colitis) syndromes. [1][2][3][4][5][6] The PSTPIP1 gene variant detected in our patient was a missense variant, similar to the variant reported in a previous patient with PAC syndrome. 5 Both patients had colitis and pyoderma gangrenosum. However, the patient with PAC syndrome developed symptoms at a younger age than did our patient. In addition, unlike our patient, the patient with PAC syndrome experienced severe acne and did not have clinical improvement with oral prednisolone.
We have found no previous descriptions of proctitis, pyoderma gangrenosum, hidradenitis suppurativa and fever occurring in the presence of a PSTPIP1 variant. Therefore, we suggest that this should be called PPHSF syndrome and should be added to the increasing number of PSTPIP1-related autoinflammatory diseases. 6