Differential Diagnosis
- Single most likely diagnosis
- Hidradenitis Suppurativa (HS): This condition is characterized by recurrent, painful abscesses and nodules in apocrine-gland-bearing areas, often with a hard, shell-like exterior and purulent discharge. The description of deep holes, itching, and the inability to express pus due to a hard shell, along with the lack of contagion and worsening with treatments, aligns closely with HS, especially given its chronic nature and difficulty in management.
- Other Likely diagnoses
- Folliculitis: An inflammatory condition affecting the hair follicles, which can lead to itchy, pus-filled bumps. While it can resemble the described condition, the depth of the lesions and their hard shell might not fully align with typical folliculitis presentations.
- Acne Conglobata: A severe form of acne characterized by large, connected lesions and abscesses. It can cause significant scarring and might fit the description of deep holes and hard, infected-appearing lesions.
- Kerion: A severe form of tinea capitis (fungal infection of the scalp) that can cause deep, painful lesions. However, its confinement to the scalp and the presence of fungal elements might distinguish it from the described condition.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cutaneous T-Cell Lymphoma (CTCL): While less likely, CTCL can present with a wide range of skin manifestations, including lesions that can mimic infections or other dermatological conditions. Its potential for severe outcomes if left untreated makes it a critical diagnosis not to miss.
- Squamous Cell Carcinoma (SCC): A type of skin cancer that can present as non-healing sores or lesions. The description of deep holes and the hard shell of the lesions, along with their failure to respond to treatment, necessitates consideration of SCC, especially in sun-exposed areas or in individuals with risk factors.
- Rare diagnoses
- Ecthyma Gangrenosum: A rare skin condition often associated with Pseudomonas aeruginosa infection, characterized by hemorrhagic pustules that can evolve into gangrenous ulcers. While it's more commonly seen in immunocompromised patients, its potential severity warrants consideration in cases of unexplained, severe skin lesions.
- Pyoderma Gangrenosum: A rare condition that causes tissue to become necrotic, leading to deep ulcers that usually start as a pimple or a bug bite. The ulcers can be very painful and can grow rapidly, which might align with the description of deep holes and hard, infected lesions, though the typical presentation and associated conditions (like inflammatory bowel disease) might differ.