Infantile Hemangioma (IH): Given the description of a congenital hemangioma covering the upper lip, nose, philtrum, and the presence of similar lesions on the back, which could be either superficial hemangiomas or port-wine stains, infantile hemangioma is a strong consideration. The fact that the upper lip is now ulcerated and appears deficient suggests the possibility of an ulcerated infantile hemangioma, which is a known complication.

Port-Wine Stain (PWS): The mention of lesions on the back that could be either congenital superficial hemangiomas or port-wine stains makes PWS a likely diagnosis for those specific lesions. However, the ulceration and appearance of deficiency on the upper lip are less typical for PWS.
Arteriovenous Malformation (AVM): Although less common, AVMs can present at birth and may have a similar appearance to hemangiomas. The ulceration and potential tissue deficiency could be indicative of an AVM, especially if there's a history of rapid growth or other systemic symptoms.

Kasabach-Merritt Syndrome (KMS): This is a rare condition associated with a vascular tumor (often a kaposiform hemangioendothelioma or tufted angioma) that leads to severe thrombocytopenia and coagulopathy. Although the primary description doesn't strongly suggest KMS, any congenital vascular lesion with signs of ulceration or potential for bleeding should prompt consideration of this diagnosis due to its severe implications.
PHACE(S) Syndrome: This syndrome involves the presence of a large hemangioma, typically on the face or neck, in association with other anomalies such as cardiac, ocular, or cerebral defects. Given the location and extent of the hemangioma described, PHACE(S) syndrome is a critical diagnosis not to miss due to its potential systemic implications.

Kaposiform Hemangioendothelioma: A rare, locally aggressive vascular tumor that can present at birth. It's known for its potential to cause Kasabach-Merritt syndrome but can also present with ulceration and tissue destruction.
Tufted Angioma: Another rare vascular tumor that can present congenitally and may be associated with Kasabach-Merritt syndrome. It often appears as a firm, indurated plaque and can have a similar appearance to infantile hemangioma but tends to be more persistent and less likely to regress.